Contraception choices affect the long-term sexual health and fertility of women and men. Data from the 1998 Canadian Contraception Study and the 2000/2001 Canadian Community Health Survey were assessed for measures of contraceptive use and familiarity with various methods among Canadian women.The oral contraceptive (OC) pill is the dominant method of contraception for Canadian women. Canadian women demonstrate high awareness of the benefits of condom use, but 75% are unaware of the female condom. Among youth, condom use drops as OC use increases. Contraception use in sexually active females aged 15–17 is fairly high, but use is inconsistent. Sexually active adolescent females report high awareness of emergency contraception but poor knowledge of the time frame within which it is most effective. Women aged 35–44 are more familiar with and likely to choose sterilization than younger women. There has also been a shift away from tubal ligation in favour of vasectomies.National data to guide policy and program development are limited. More data are needed on contraception use among males, and factors affecting accessibility, adherence and negotiation of choice. The importance of dual protection, and correct and consistent use of the chosen contraceptive method must be communicated to younger Canadians, as well as health care providers and educators. All women of reproductive age should be made aware of emergency contraception methods and increased efforts on sexual health promotion and education are required. Further research is essential to develop expanded contraceptive choices. Contraceptive choices affect the long-term sexual health and fertility of women and men, particularly when contraception is not used correctly or consistently. For many women, the ability to control their fertility has enhanced their ability to control their lives; however, with this power has come a greater responsibility for contraception in a relationship. Given that the majority of contraceptive methods available are made to be used by women and that the consequences of a contraceptive failure can have a greater impact on the life and health of a woman than on her partner, this is a vital issue in women's health. Ideally, in any relationship both partners will discuss the most appropriate method of contraception and be committed to using it correctly and consistently. The context in which men and women make decisions related to contraception has changed with the advent of oral contraception (OC) some 40 years ago and, more recently, with the increased awareness of HIV/AIDS and sexually transmitted infections (STIs).The decision to use one contraceptive method over another is influenced by personal choice, perceptions of efficacy, personal risk, access, age, cost, gender, education, ethnicity, marital status, current number of children, sexual orientation, pattern of sexual activity and level of co-operation between partners.The objectives of this chapter are to provide a brief historical perspective of contraception; highlight recent trends in contraceptive use among Canadian women; examine their familiarity with various methods, including emergency contraception; consider the factors that influence choice across life stages and differences in this regard between the sexes; and make recommendations based on this information. The chapter will focus on two of the leading contraceptive methods, OC and the condom.History has demonstrated that, for centuries, women and men have been using various methods of contraception, some of which were pernicious to women's overall health, to prevent pregnancy and control their fertility. In CanaCross-sectional data from cycle 1.1 of the 2000–2001 Canadian Community Health Survey (CCHS) were analyzed. Results from the 1998 Canadian Contraception Study (CCS), other surveys and research were examined to provide a picture of current contraceptive practices among women of various ages and the factors that influence their choices. The 1998 CCS compared four national surveys of contraceptive use in Canada: the Canadian Fertility Study (CFS) (1993) and three Canadian Contraception Studies .Introduced in the 1960s, oral contraception is widely used around the world. According to the 1998 Canadian Contraception Study, OC is the dominant method of contraception for women in Canada, used by over 28% of all women and 43% of sexually active women[Condoms are an effective method of birth control and currently provide the most reliable barrier method for protection against HIV and STIs. The estThe female condom, or vaginal pouch, is a relatively new method which gives women control of a barrier method and provides some STI protection. The CCS revealed that only 25% of the women sampled had heard of the method, although 41% of young unmarried women 15 to 17 years of age were aware of it. No one reported using it as a method of contraception, and only 3% had a favourable attitude towards the female condom[Dual protection is defined as any method of birth control combined with a condom. Dual protection prevents pregnancy and prevents the transmission of an STI, but it should be noted that some STIs, such as human papillomavirus (HPV), can exist outside the vagina or at the base of the penis, and the protection afforded by a condom is not absolute. Particularly important for younger people or those not in mutually monogamous relationships is the fact that dual protection can help maintain good sexual health throughout an individual's lifetime.Studies on dual method use are limited, but several reasons can be hypothesized as to why concurrent use with a condom appears to be low. First, individuals seem to perceive pregnancy as the greatest imminent threat, and once this has been addressed their motivation to take further measures is low. Second, some methods are compliance-dependent, such as OC or condoms, and others compliance-independent, such as sterilization or the intrauterine device (IUD). Those using compliance-independent methods may be less likely to have condoms available or to take extra measures.Often referred to as the "morning after" pill, emergency contraception (EC) has been available for more than two decades in North America and Europe, offering an effective choice after unprotected sex or contraception failure, or for use in cases of sexual assault. EC is highly effective in preventing pregnancy if taken within 72 hours of unprotected sex. It works by either preventing ovulation or changing the lining of the uterus so that implantation cannot occur. EC will not work if a woman is already pregnant[A survey conducted by Langille and Delany of 14- to 19-year-olds at a high school in Nova Scotia showed that 80% of the girls had heard of EC, but only 10% were aware of the time limits within which EC is effective. Overall, they had a poor understanding of the risks, benefits or effectiveness of EC. These young women had learned about EC for the most part through their sexual health education classes in grades 7 to 9. Only 2% had heard about it through their physician[The challenge facing policy makers is to raise awareness about the potential role of EC in women's reproductive health. The cost of medical care associated with an induced abortion is estimated to be $618, whereas the cost of a physician visit and prescription for EC is approximately $32.27. This siThere are some new contraceptive methods on the horizon but not yet available in Canada. Vaginal ring and injectable monthly contraceptives are combined estrogen and progestin methods that are highly effective and, because they do not require a daily ritual, may improve compliance. Progesterone-releasing intrauterine devices and implants offer effective choices for women for whom estrogen is not recommended.Another new option for Canadian women is the contraceptive patch, approved for use in Canada in August 2002. It works in the same way as OC, but in the form of a once-a-week patch. The patch, which is the size of a match-box, is worn for three consecutive weeks, and then a patch-free week follows.Expectations for a male pill in the near future have been lowered, as clinical trials in China funded by the World Health Organization (WHO) resulted in several serious side effects. This trial has been stopped, but research into other options does continue. AnotherResearch into microbicides, which can kill viruses, bacteria and fungi, and sperm, is under way, though it will likely be many years before these precautionary measures become widely available. The potential of an insertable gel  in combatting HIV and STI is huge and would give women control over both pregnancy and STI prevention. There has been limited investment by pharmaceutical companies, only 1% of funding for microbicides coming from the private sector. Microbicides will be particularly valuable for women in abusive relationships, for sex trade workers or for those with partners involved in outside relationships.Analysis of CCHS data indicates that 17.7 % of the women aged 12 to 50 who were surveyed reported using OC when asked about medications taken in the previous month. It is important to note that the module on medication in this survey was asked only in Ontario, and the question set referred to all medications, not only contraceptives. Women between the ages of 18 and 29 reported the highest usage of OC, and single women reported higher usage, as shown in Figure p < 0.001) among single women. Women who described themselves as "white" were significantly more likely to use OC than those from other racial or cultural backgrounds . Finally, a correlation between OC usage and education was also observed, in that women who had graduated from high school or had any post-secondary education were significantly more likely to use OC than women with less than a high school diploma [The CCHS results shed light on factors other than age that affect OC use. Women in the low to low-middle income range were less likely to use OC in the previous month than their higher-income counterparts. Rural versus urban living had no impact on usage, but partnered women (married or common-law) reported significantly lower usage rates, 14.7 % versus 21.4% . with OC and condoms over time, their familiarity with other methods, such as sterilization, withdrawal, the diaphragm, the IUD and the rhythm method, has steadily declined since 1984. This maFinally, the percentage of women who were not using any method of contraception increased from 21% in 1984 to 25% in 1995, a finding that may be explained by the aging of the population.Contraception use at sexual debut among women in the 15 to 17 age group is quite high, 80% reporting its use the first time they had intercourse, according to the CCS. While the sample was small and did not allow for testing of statistical significance, it provides an indication that many adolescents are using contraception at sexual debut. With regard to consistency of use over the previous six months, however, only 60% of unmarried teens 15 to 17 years of age reported always using contraception and, as noted earlier, 22% of this sexually active group rely on withdrawal.The rate of teenage pregnancy in Canada remains high. A Statistics Canada report estimated that in 1997 the number of women aged 15 to 19 who had given birth was 19,724, and the number who had had an induced abortion was 21,233. AlthougCanadian studies show that rates of condom use drop as use of OC increases among youth, especially with a main partner. Condom Aboriginal youth, street youth, sex trade workers and other marginalized youth are not represented in these studies, and although they are small in number they may be at higher risk of both unintended pregnancy and STIs. More targeted research is needed to guide program development and to ensure that, once developed, programs meet the needs of these Canadian youth in ways that are appropriate, accessible and culturally sensitive.Women in the 18 to 29 age group are often completing their studies, establishing themselves in careers, and entering into long-term relationships while at the peak of their fertility. It follows that this group has the highest usage of contraception. The popularity of methods in this age group, in descending order, are OC, condom, IUD, diaphragm, foam, rhythm and withdrawal, and "other." Although the popularity of OC has changed very little, use of the condom was higher in 1995 than 1984, indicating that safer sex messages are having some effect.Fisher and Boroditsky examined the sexual activity and contraceptive choices of single Canadian women aged 15 to 17, 18 to 24, and 25 to 29. These women are aware of and have positive opinions about OC and condoms, but their awareness and opinions on other methods, such as the female condom, emergency contraception or injectable methods, were limited and not favourable. These young women reported a high level of contraceptive use at first and last intercourse with a current partner, but over time they were less likely to continue dual protection and may have used less reliable methods, such as withdrawal. The authors suggested that efforts should be made to encourage consistent use of appropriate contraceptive methods over time.A 1999 U.S. study examined the differences in perceptions and priorities of men and women aged 20 to 27 with regard to contraception. Women, particularly married women, ranked the prevention of pregnancy as most important. STI prevention and absence of associated health risks followed or were viewed as equally important. Men ranked pregnancy and STI prevention equally as the most important. Single men and women ranked the importance of STI protection higher than the married group. The differences between the perceptions of the sexes could be attributed to four factors: (1) women have a higher exposure to information about contraception, as it is often considered the domain or responsibility of women; (2) women tend to have more experience in making choices about contraception use for the same reason; (3) the actions required by men and women vary depending on the method used; and (4) men and women do not perceive the risk of an unwanted pregnancy or STI equally.Men and women agreed in their ranking of OC and the condom as to ease of use and spontaneity. They did not, however, agree on the method that most interfered with pleasure: women identified the diaphragm and men the condom.According to the CCS, women aged 35 to 44 reported a higher level of familiarity with sterilization than younger women and lower familiarity with reversible methods. This group held a much more positive attitude about male and female sterilization and the IUD. Although women aged 35 to 44 viewed OC quite positively, there was some indication that they were poorly informed about its risks and potential long-term benefits, particularly with the arrival of low-dose oral contraception, which allow many women to use this method for longer than traditional oral contraception[When asked about the method used, single women relied on the pill and condom, and married women were most likely to rely on sterilization, of themselves or their partners: 23% of married women aged 35 to 44 reported using sterilization as their method of contraception, 10% of themselves and 14% of their partners. A change in contraceptive method is common in this group, with the switch to sterilization reflecting the desire for a permanent contraceptive method. Twenty-three percent of married women whose previous method had been the pill changed methods on their physician's advice[A study conducted in the United States examined two U.S. data sets on sterilization, Cycle 5 (1995) of the National Survey of Family Growth and the 1987–1988 National Survey of Families and Households, to analyze why tubal ligation is so much more common than vasectomy. The authors concluded that some individuals make a decision to be sterilized without considering sterilization options for their partners, and this is more likely if they are unmarried. Factors that influence the decision include marital status, and surprisingly high numbers of unmarried women seek sterilization. Also, there are low rates of vasectomy among men in cultural minority groups and high levels of tubal sterilization among women in these groups. Age and current number of children at last birth play a role in the decision. Education is also a factor, given that the higher the woman's educational level the less likely it is that a couple will opt for tubal ligation and the more likely that they will choose vasectomy, whereas couples with the same level of education will more likely choose tubal ligation Finally, religion affects choice, given that fewer Catholics undergo vasectomy or tubal ligation than Protestants.Canadian women indicate that they would prefer their partner to undergo a vasectomy, and for many reasons. The male procedure is simpler and has fewer risks: a 15-minute office procedure under local anaesthetic versus a 30-minute surgical procedure under general anaesthetic[Despite the availability of excellent data from the CCHS, the 1998 CCS and Canadian fertility studies that are frequently cited in this chapter, there are limited Canadian data on contraceptive use by women of all ages and even fewer on contraceptive use by men. More research is needed on accessibility, adherence, cause of unintended pregnancy, and negotiation of choice and use of contraception with one's main partner in order to provide a clearer picture of contraceptive use in Canada today. A further limitation is the lack of data on Aboriginal people, street youth, sex trade workers and other marginalized populations.Although there are more choices of effective methods of contraception available to Canadian women today than in the past, research shows that not all women have the same level of familiarity with or access to the various methods. Messages about the importance of correct use and adherence to the contraceptive method chosen are a vital component of the information needed by women. Until such time as there are more effective options of contraception available to men, women need to remain diligent to ensure that the method used provides the level of protection required. The challenge facing policy makers and program administrators will be to increase awareness and knowledge among women of all ages to help them make the best contraceptive choices throughout their lives.Consideration of contraceptive methods should be balanced between the objectives of reducing unintended pregnancies and the need for STI protection. Before the pandemic of HIV, the focus of policy makers in this area was population growth, but given the serious consequences of an STI, contraception has the potential to offer broader protection for women and men.The following recommendations are made:• Increase efforts in sexual health promotion and education to raise awareness in Canadian women of all ages about the advantages and disadvantages of the various contraceptive methods available to them.• Heighten awareness of the importance of dual protection, particularly in younger women and men as well as in physicians, health care providers and educators. Women place higher emphasis on pregnancy prevention than STI prevention, which may be a result of lack of information.• Adherence to the contraceptive method chosen is critical to the effectiveness that it offers. Counselling concerning the choice of contraception method must take into account the individual needs of each woman and methods that require co-operation from a partner may not be appropriate for all women.• Raise awareness of access to emergency contraception in women of all ages. This should include the time frame for which EC is effective and information on where EC can be accessed.• Increase resources to fund research and trials associated with new, reversible contraceptive methods for men and the development of safe and effective microbicides.The views expressed in this report do not necessarily represent the views of the Canadian Population Health Initiative, the Canadian Institute for Health Information or Health Canada.


Over the last 20 years, much has been achieved in controlling blindness in children. Prior to the launch of VISION 2020, a number of international initiatives and programmes had raised the profile and increased interventions for child health and survival, which also had a positive impact on eye diseases and blindness in children, e.g. the Expanded Programme for Immunisation (EPI)(1974) and the Global School Health Initiative (1995). Since 2000, the United Nations' Millennium Development Goals have emphasised the need to promote child health and survival.Since VISION 2020 was launched in 1999, controlling blindness in children has been a high priority. Child Eye Care Centres are being established with well-trained, well-equipped teams, particularly in Asia. Programmes for detecting babies with retinopathy of prematurity (ROP) are expanding in Latin America, India, China, and other countries in Asia. Many school-going children are having their visual acuity measured and those with refractive error are being provided with spectacles. Finally, there is improved availability of affordable consumables and equipment, such as paediatric low vision devices, small diameter intraocular lenses, and spectacles for children.This article presents an overview of what we have learnt over the past twenty years and outlines some of the challenges we still have to face in order to control avoidable blindness in children and adequately support those with incurable visual loss.In 1988, there was little information on the magnitude and causes of blindness and visual impairment in children. At that time, most of the information on causes had come from examining children in schools for the blind and prevalence data were very limited. However, we have since made substantial progress, both in collecting data and in finding ways to estimate the magnitude and causes of childhood blindness.In 1990, the World Health Organization (WHO) organised the first meeting of experts on the prevention of blindness in children; they estimated that there were 1.5 million blind children in the world.2In 1990, experts agreed that corneal scarring, mainly from vitamin A deficiency and measles, was the major cause of childhood blindness in most low-income countries.6During the 1980s, it was realised that vitamin A deficiency was an important cause of child mortality and that high-dose vitamin A supplementation significantly reduced child deaths, even in communities with low levels of clinical xerophthalmia. Intermittent high-dose vitamin A supplementation is an important public health intervention and approximately 500 million doses are given annually throughout the world at a cost of approximately US $1 per dose. As a result, the prevalence of vitamin A deficiency has declined in many regions of the world. There is also evidence that blindness in children due to corneal scarring has also declined. For example, in Uganda, 53% of all blind children born between 1951 and 1965 were blind from corneal scarring, compared with 14% for children born between 1980 and 1995.Measles immunisation is another large-scale public health intervention to reduce child morbidity and mortality. Since the launch of EPI in 1974, coverage with measles immunisation has increased to target levels in most regions. The numbers of measles cases and measles-related deaths have declined as a consequence. Measles epidemics are now relatively rare and measles-related corneal blindness has also declined. As with vitamin A deficiency, there are still communities of children at risk, particularly in sub-saharan Africa, where the majority of measles cases and measles-related deaths now occur.There is no reason to be complacent, as there is evidence that under-five mortality rates are no longer declining at the same rate as in earlier decades in the poorest parts of the world. Our role as eye care professionals is to advocate for children – when we see a child with corneal ulceration from vitamin A deficiency or following measles, we should not only treat the child, but we should also inform the relevant authorities so that they can improve their programmes.Because corneal blindness is declining in many countries in Africa and Asia, cataract is becoming a relatively more important cause of avoidable blindness. The management of cataract in young children has changed dramatically over the last 20 years. When intraocular lenses (IOLs) were first used in the late 1970s, they were thought not to be suitable for children. Over the last decade, smaller, high-power IOLs, suitable for children, have become available; surgical techniques and equipment have also evolved. Many paediatric ophthalmologists now insert IOLs in children as young as 12 months of age. However, this technique requires considerable expertise and a vitrectomy machine, as the posterior capsule and anterior vitreous have to be removed in young children. Long-term follow-up is also crucial to manage visual axis opacities and to ensure the child is given optimal optical correction and low vision devices, if required.In the early 1990s, it became apparent that an epidemic of blindness due to ROP was occurring in middle-income countries.Little was known about the magnitude of vision loss due to refractive error in children until the late 1990s. Since 2000, WHO has worked with the National Eye Institute, USA, to undertake standard, population-based surveys of the prevalence of refractive error in all regions of the world among children aged five or seven up to 15 years. The findings show that refractive errors are more prevalent in children in Asian countries than in other regions, and that myopia, which increases with increasing age, is the commonest refractive error in older children. Myopia is also more common in children from urban areas than in those from rural areas. The current thinking is that myopia is caused by the influence of genes as well as environmental factors, and that outdoor activity may protect children from myopia. We also know from studies in TanzaniaRecent data from the studies of refractive error mentioned above suggest that the prevalence of functional low vision  is approximately twice the prevalence of blindness: there are almost 3 million children worldwide who have the potential to benefit from low vision care.The control of blindness in children is a VISION 2020 priority because the number of ‘blind person years’ resulting from blindness starting in childhood is second only to cataract. If VISION 2020 targets for children can be met, the global prevalence of blindness will have fallen from 7.5/10,000 children (in 1997) to 4/10,000 children by the year 2020. The number of children who are blind will decline to approximately 800,000.Visual loss from refractive error and cataract is treatable, and blindness from vitamin A deficiency, measles, or ROP is potentially preventable. As eye care workers, we must provide the relevant information, services, and support to reduce blindness and visual impairment in children from these avoidable causes. We also need to ensure that children with incurable visual loss are not denied their equal right to education and to lives that are fulfilled and rewarding.Integrating eye health into broader child health initiativesInternational initiatives for the promotion of child healthPrimary health care  for most of the preventable eye conditions.Tailoring services specifically for childrenNot treating children like small adultsAdopting a holistic, child-centred approach, which includes parents and carersDeveloping and emphasising the sub-specialty of paediatric ophthalmology, from residency programmes through to service deliveryPlanning services for a catchment population of 10 million people, rather than the 1 million used for adult blindness.Increasing uptake of servicesWe have to be much more proactive in finding children who need treatment, particularly girls We must try to make services affordable for children (free or greatly subsidised) and inform the community of how much is being chargedHealth education for mothers is crucial: they should know how to prevent potentially blinding conditions and where they should go if their child has a problemHealth education for children, girls in particular, is equally important: they are the parents of the futureThe current focus of school programmes on refractive error alone means that opportunities for health promotion and education are being missed. School-going children have siblings and parents at home.Recognising the importance of education and rehabilitationMany children attending eye care services have visual loss from untreatable conditions. It is our responsibility to ensure they are seen in low vision clinics and referred for education and rehabilitationAs avoidable causes are declining, a greater emphasis needs to be placed on preventing disability through education and rehabilitation.Ongoing research activities to improve programmes


A couple of decades ago, hospitals or psychiatric institutions were in charge of caring for patients with schizophrenia; however, nowadays this role is performed by one or more patient's relatives. Evidence shows that informal caregivers experience negative changes in their quality of life (QOL). The aim of this study is to review the main factors associated with the QOL of caregivers of people with schizophrenia.A search through databases from journals published last decade between 1998 and 2008 was performed. In accordance with the inclusion criteria, titles and abstracts of citations obtained from the search were examined independently by two authors and irrelevant articles discarded. The full text of those studies considered relevant by either reviewer were obtained and assessed independently. Where differences of opinion rose they were resolved by discussion. Out of the 258 references, 37 were included in the review.Studies which assessed factors associated with caregivers of people with schizophrenia's quality of life were included and the information summarized.Evidence suggest that physical, emotional and economic distress affect negatively caregiver's QOL as a result of a number of unfulfilled needs such as, restoration of patient functioning in family and social roles, economic burden, lack of spare time, among other factors.Decreased QOL may be associated with caregivers' burden, lack of social support, course of the disease and family relationships problems. In addition, in developing countries, QOL is affected by caregivers' economic burden. High quality research is needed in order to identify factors associated with QOL over time and testing the efficacy of interventions aiming to improve QOL in caregivers of patients with schizophrenia. Nowadays family has taken functions which were performed in the past by psychiatric institutions. This change highlights not only the relevance of emotions and affections within a family, but also the great amount of burden experienced by these relatives while taking care of a psychotic patient as well. Thus, "informal care" is playing a significant role in development and evaluation of health programs and policies .Main caregiver has been defined as the person belonging to the patient's informal support system who takes the care and is responsible for the patient, and who commits most of his or her time to that task without receiving any economic retribution . There iIn 1993, The WHOQOL  Group  defined Martens y Addington  observedIn the health field, QOL (a construct closely related to burden) is one of the most important components associated with delivering an integral service to an ill person and their family, emphasizing the subjective perspective held by the patient and the family. In this context, one of the main objectives is the development of supporting activities rather than reducing symptoms and preventing relapses only.Until recently, due to the inclusion of new drugs, research on QOL has been focused on schizophrenia patients rather than their caregivers. Currently, informal and formal caregivers are being considered as a valuable component of an integral treatment for patients, thus their QOL and burden are being evaluated -18.This review tries to answer the following questions: a) What variables are related to QOL damage in caregivers of patients with schizophrenia? b) Does relative's QOL differ substantially among developed and developing countries? c) Which objectives should aim at future researches.A systematic search was carried out using the following electronic databases: MEDLINE via PubMed, Web of Science and PsycINFO. The following keywords were used: quality of life, burden, schizophrenia, families, caregivers, and a combination of them. The search comprised primary and secondary studies and was limited to references published from 1998 to 2008. Potential studies were included if they considered a primary family caregiver and focused on caregiver's QOL related to schizophrenia. Since this review aimed to identify variables related to QOL in caregivers of patients with schizophrenia, descriptive, cross-sectional and qualitative studies were included.The hits retrieved by database were: MEDLINE via Pubmed (73), Web of Science (93) and PsycINFO (49). In accordance with the inclusion criteria, titles and abstracts of citations obtained from the search were examined independently by two authors and irrelevant articles discarded. The full text of those studies considered relevant by either reviewer were obtained and assessed independently. Where differences of opinion rose they were resolved by discussion. Out of the 258 references, 37 were included in the review.Most reviewed studies had a "cross-sectional" design showing a low level of evidence available. The less were of "prospective cohort" type, only one of them was a "case control" study, and a study alone used qualitative methodology. To assess caregiver QOL, different methods and instruments were used; therefore, comparison among studies was difficult. The amount of caregivers interviewed ranged from 30 to 288. It is likely that some studies were not sensitive enough to detect any significant association with caregiver burden and/or caregiver QOL.The correlations between different variables and caregiver's QOL included in the discussion came mainly from descriptive studies. In order to summarize the results taking into account the heterogeneity and the poor quality of the studies, the authors agreed that an association between any factor and caregiver's QOL was considered in the discussion when it was found statistically significant in the original paper (p < 0.05) and was present in more than 10% of the papers reviewed. This allowed us to discuss those associations that were significant form a statistical point of view and more frequently studied.Additional file Despite differences among countries, studies carried out in different parts of the world show similar outcomes. Following we describe the factors that were found associated with caregivers' QOL.Several studies stated that appearance of psychotic symptoms or the course of the disease produce an important level of burden -37.Caregivers' health was highly deteriorated. Stress problems, anxiety, and depression were observed in several studies -34. InteWorking life was also significantly affected. Caregivers must leave their jobs, modify their working hours or change to another job. Moreover, in some cases, stress seemed to be associated with a triple shift: job, household duties, and care for a patient -39.The last dimension evaluated was economic burden. Economy issues produce concern in caregivers due to expenses in different areas, e.g. drug therapy and treatment. Regarding this, there is a difference between developed and developing countries. In countries such as Chile, Nigeria, and India caregivers expressed more concern in this dimension, likely caused by scarcity of community and health resources ,22,24,40Family dynamics were affected due to the presence of disagreements, conflicts, and even violence among its members. In addition, some close relatives might go away avoiding having to take care of the patient ,37,39-42Damage in caregiver social life and a lack of social support has lead to caregivers complaints towards treatment delivered by health institutions and their professionals ,40,43,44Some researches have analyzed cultural variables in populations that have not been frequently included in research. Caregivers belonging to an ethnic minority have the worst QOL and those from countries with more traditional families use religion as a way of coping ,34,43,45Finally, most of the studies show that the mother is the one who takes main care of the patient and has worse QOL than other type of informal caregivers caused likely by her caring chores ,30,35,38The variety of methods used in the reviewed studies makes comparison among them difficult. It would be important to achieve an agreement regarding what instrument is the most appropriate to employ in the case of caregivers of patients with schizophrenia in order to measure their QOL. In addition, future research is needed going beyond the cross-sectional design. It should be considered at least a case-control design having comparative groups clearly defined and blind , or studies using self-report instruments to measure this construct and other variables in which disturbance variables are in control. This would allow obtaining better evidence about factors associated with QOL of caregivers of patients with schizophrenia.Despite the fact that good quality evidence is required, a recent trend towards studying this subject on diverse family groups can be observed.Regarding the aims of this review, some similarities were found in the results obtained from the studies reviewed:a) What variables are related to QOL damage in caregivers of patients with schizophrenia?Main variable was emotional burden on caregivers as a consequence of their role, lack of social and working support, course of the disease, and disruptions in family life. All these factors were associated with a considerable damage of QOL.b) Does relatives' QOL differ substantially among developed and developing countries?The feeling of being exhausted seems to be generalized to relatives from different countries as well as cost associated with mental disorders, however, major differences regarding QOL appear to be related to having a better access to and higher availability of health and economic resources for these caregivers. In developing countries, economic burden may be playing an important role in relative's QOL. Lack of psychiatrist, day hospitals, access to drug treatments, among others, could generate a considerable concern in these relatives.c) Which objectives should aim at future researches?There is a need for treatment and follow-up as much as improvements in family intervention programs delivered by health services. These factors should be considered in future research in this area. Program design should take into account socio-cultural characteristics of the population attending a health service. Efficacy of such interventions needs to be proved since they could be beneficial not only for the patients, but also for the caregivers.This review has limitations. The study design of most reports was cross-sectional reflecting the lowest level of evidence. This has the following implications for the results:a) Associations found across studies may have been influenced by different sources of bias making the internal and external validity of them questionable. For example, recruitment strategies and sampling varied a lot across studies. Most of the studies employed purposive samples where interviews were applied only to those who were willing to participate in a research. Therefore, caregivers studied may have not been a representative sample of caregivers of patients with schizophrenia.b) The criteria adopted for including associations in the discussion might have excluded those that maybe were clinically significant but did not reach statistical significance.c) The descriptive nature of most of the included studies made the use of quantitative pooling methods  not possible. As mentioned previously, good quality studies are needed in order to assess the impact of interventions aimed to improve caregivers of patients with schizophrenia's QOL.In summary, it seems that "informal care" is playing an important role in the care of patients with schizophrenia and this issue needs to be thoroughly analyzed because of the high psychopathological risk experienced by informal carergivers.QOL: Quality of lifeThe authors declare that they have no competing interests.ACU contributed to the design and coordination of the study. JGM was responsible for primary study design and supervision of data collection. CMC was a methodologic consultant, assisted with data analysis and interpretation, and participated in manuscript editing. All authors read and approved the final manuscript.Variables associated with QOL in family caregivers of patients with schizophrenia. The table shows the variables associated with QOL in family caregivers of patients with schizophrenia found in the literature review [e review -53.Click here for file


The fertility of a chicken's egg is a trait which depends on both the hen that lays the egg and on her mate. It is also known that fertility of an individual changes over the laying period.Longitudinal models including both random genetic and permanent environmental effects of both the female and her male mate were used to model the proportion of fertile eggs in a pedigree broiler population over the ages 29-54 weeks.Both the male and the female contribute to variation in fertility. Estimates of heritability of weekly records were typically 7% for female and 10% for male contributions to fertility. Repeatability estimates ranged from 24 to 33%, respectively. The estimated genetic variance remained almost constant for both sexes over the laying period and the genetic correlations between different ages were close to 1.0. The permanent environment components increased substantially towards the end of the analyzed period, and correlations between permanent environment effects at different ages declined with increasing age difference The heritability of mean fertility over the whole laying period was estimated at 13% for females and 17% for males. A small positive correlation between genetic effects for male and female fertility was found.Opportunities to improve fertility in broiler stocks by selection on both sexes exist and should have an impact throughout the laying period. Fertility is a trait of major interest in the broiler industry, primarily because of its effect on chick output. Also, as there is a negative correlation between growth and fertility, especially in naturally mated flocks , selectiFertility in poultry is traditionally regarded as an independent trait either of the male or the female, but genetic and non-genetic factors originating from both the male and female affect egg fertilization and embryo development . FertiliFactors affecting fertility which originate from the male include several sperm quality traits such as sperm metabolism, semen concentration, sperm motility, and the percentage of abnormal or dead sperm cells . BehavioSeveral approaches to analyze aspects of fertility in poultry can be found in the literature but none are all inclusive. For example, models used in recent analyses include fitting direct and maternal genetic effects for female fertility , fittingThe different potential inputs into fertility, including sire, dam and offspring genotypes over a protracted period of life, provide questions about the genetic control of the trait which may have implications to other life history characters. Hence the present study was undertaken to investigate the various contributions to fertility by estimating genetic parameters for female and male fertility simultaneously using an animal model, taking into account the longitudinal nature of the trait by using random regression models.th day of incubation to record the number of infertile (candled clear) eggs. Fertility was defined as the proportion of the total number of eggs set in each laying period that were fertile (as determined by candling). For the male, the total number of eggs set was the sum of all settable eggs laid by all the hens in the pen within the given period, while for the female, number of eggs set related only to the total number of settable eggs laid by the individual female within the period. Males were usually replaced if weekly fertility in a pen was consistently low for a period of five weeks. Data from such males were excluded from the analysis.Fertility data from a fully pedigreed pure broiler line were obtained from Aviagen Ltd, a primary broiler breeding company in the UK. The data comprised records of 555 males mated to 3755 females over a period of five years. Birds were housed in floor pens at a ratio of one male to ten females of the same age. The hens were trap nested with eggs set for incubation every week. Eggs were candled on the 7The time trajectory used in this analysis was the age of the hen when the eggs were hatched. Records from ages 29 to 54 weeks were included, and comprised a total of 66104 weekly fertility records derived from a total of 342797 eggs set. The mean number of eggs set was 5.19 and, of the 66104 records, only 1557 were based on one egg. In the main analysis all weekly fertility records were used without weighting by the number of eggs set. The average weekly fertility across hens and over age is shown in Figure All analyses were undertaken using ASREML , which pFertility was described by the following random regression model using Legendre polynomials as covariates:where:yijkn is a fertility record, i.e. the proportion of eggs set that were fertile, for incubation at the n-th week of age by female k mated to male j in POU i,POUi is a fixed effect of contemporary group (which incorporates genetic trend),bm is the m-th fixed regression coefficient,ajm Mand ajkm Fare the m-th random regression coefficients for the additive genetic effect of, respectively, male j and female k mated to male j,pjm Mand pjkm Fare the corresponding coefficients for permanent environmental (PE) effects,zmn is the value of m-th degree Legendre polynomial at week n,eijkn is a random residual effect,m1 to m5 are degrees of covariates fitted to fixed, genetic, and permanent environment effects, where m = 0 denotes a constant term and m = 1 a linear regression coefficient etc.Since the use of random regression models fitting hen and mate genetic and permanent environment effects simultaneously for fertility of eggs is novel, it was necessary to consider a large array of models to determine which was the most plausible and provided an adequate description of the data. A subset of the many models fitted and corresponding likelihoods is shown in Table m = 3) was used to model the fixed effect of age on fertility, as this described the observed mean weekly fertility profile , was assumed to be different for each week of the age trajectory as fitting homogenous residuals over the whole or for three separate time segments gave much lower likelihoods, and we had no prior knowledge of the pattern of the error variances.The residual variance, Var(m2 = m3 = 0) in part because these models described the data almost as well as those of higher degree (see later), and in part because the simple models allow interpretation in terms of a single genetic correlation.In order to estimate the genetic correlation of male and female effects on fertility, a covariance between male and female genetic effects was also fitted in some models. This refinement was restricted to models with constant genetic effects (m2 = m3 = 0) and linear random regression PE terms (m4 = m5 = 1). However, it was not pursued further, because the relative size of all the genetic and PE components was found to be essentially the same as in the corresponding analysis using the unweighted model (data not shown).An unweighted analysis was used, but just simply weighting of weekly observations by the number of eggs set would not have been adequate because there was a high variance between parents in fertility. To accommodate both variation in numbers set per week and real differences between families, an analysis using a threshold model, which is much more computationally demanding, was undertaken fitting sire and dam genetic effects as constant  and non-genetic individual specific  effects. Variances of the random effects (genetic and PE) of both male and female on fertility were significantly greater than zero.Variances due to non-genetic permanent environment effects of males (across mates and over time) and females (across time) were large and much higher than the corresponding genetic effects at all ages Figures  and 3. TThe heritability for both male and female effects is plotted as a function of weeks in Figure Random regression analysis enables estimation of correlations between any pairs of age points. Examples of estimated genetic correlations and correlations of permanent environment effects for an early, mid and late week of production are given in Tables The inclusion of a genetic covariance between male and female genetic effects (fitted as constants) in the model did not result in a significant increase in the log likelihoods Table . The estThe present study shows clearly that both the female and her male mate influence the fertility of the egg, and that the contribution of each sex is influenced by both genetic and permanent environment components. Therefore, the male contribution is important, not only because each male is mated to many females but because, in a sire line, the individual male and his male descendents have a major influence on the efficiency of the multiplication pyramid. Furthermore, while the results pertain directly to domesticated poultry, there is no reason to doubt that there will be contributions of both sexes to egg fertility in natural populations of birds. However, obtaining adequate data to support or refute this conjecture in the wild would be difficult.The conclusions are, of course, dependent to some extent on the model which is used for the analysis. We have not, for example, included maternal genetic effects because we considered it is more important to include the male genetic and permanent environment components when analyzing the trait as, essentially, one of the direct effects of the male and female mates, both of which had a large influence. With what are basically binary data, alternative analyses to cater for the heterogeneity in variance can be undertaken. For example a threshold model has been fitted in Bayesian analyses to data on fertility and other egg production traits in egg laying stock, but with the trait analysed solely as one of the female ,20. HoweThe random regression analysis appeared to show inflated values of the permanent environment terms towards the extremes of the laying period, particularly when fitting a linear regression for PE terms. Such a result is often considered a typical feature of the random regression model ,22; but The fertility in this line reached a peak, remained at a high level for some weeks and then slowly declined Figure . VariousOur study shows that the genetic correlation between fertility at different ages for both males and females was very high across ages and was close to one for the male component Table . The conh2 = 6.7%; repeatability = 22%) using a threshold Bayesian model [The heritability of fertility estimated in this study was low at all ages. This is not surprising as it is a fitness related trait. Both male and female components increased initially to a peak, at about 9% for the female and 11% for the male, and then declined with age Figure . For coman model .Higher heritability and accuracy of selection may be obtained by averaging fertility over several weeks of set, either by pooling over eggs or by averaging weekly fertilities. However, in view of the high PE variances, the increase in heritability is not great. For the simple average of weekly fertility records, we predict it would reach 13% for females and 17% for males. Presumably, if all records were pooled with appropriate weightings and corrections for week of laying effect, somewhat higher values would be predicted. The genetic correlation between ages was high for both sexes, particularly males, which indicates that early records of fertility can be used to make breeding decisions and that there are limited opportunities to specifically improve fertility in older flocks, which is when production is most limited. Even so, basing selection decision on records from the early stages alone, gives no emphasis to the important issue of persistent fertility as the flock ages.The genetic correlation between male and female fertility used here refers essentially to the correlation between the fertility of eggs produced by daughters and by the mates of sons. The correlation was positive in our study but moderate and non-significant (0.15), indicating that improvement of one sex would be slightly beneficial, and certainly not harmful to the other, but that selection on records of both sexes would be needed for maximum improvement of overall flock performance. This could also be achieved by fitting a sire-dam multivariate BLUP model using cumulative records during the laying period from which breeding values for fertility of both sexes can be obtained for each candidate for selection.Several interesting questions remain for future research. One question is the magnitude of the genetic variance of hatchability after candling at 7 days, and its correlation with (pre-candling) fertility. Another one is the correlation between fertility and performance traits such as growth rate, although the analysis is not straightforward as only selected birds have the opportunity to breed. This also implies that, if the correlations are high, there may be biases in the current estimates of genetic variances and heritability as the data have, in effect, been censored. As this study shows, such analyses have to cater jointly for effects of both sexes and, for the reproduction traits, incorporate both genetic and permanent environment effects.The authors declare that they have no competing interests.All authors conceived the study, contributed to methods and to writing the paper and also read and approved the final manuscript. AW undertook the analysis and wrote the first draft. Data from Aviagen were prepared by VEO.


Preventing Chronic Disease (PCD) celebrates the completion of a highly innovative and bold reproductive health surveillance initiative: the Brownsville-Matamoros Sister City Project for Women's Health (BMSCP). This project, sponsored by the Centers for Disease Control and Prevention (CDC) and made possible through binational institutional collaboration, met the challenge of obtaining comparable reproductive health data on both sides of the US-Mexico border to examine the unique reproductive health challenges found in the border region. Heretofore, no such reproductive health data or mechanism to obtain such data existed or was even thought possible. As the articles and editorials in this issue indicate, the BMSCP has been successful.This issue of As a public health professional who has lived and worked in both countries, I address 3 issues: 1) opportunities and benefits from the BMSCP experience that go beyond the border region and could improve the reproductive health of women throughout both countries; 2) lessons learned to enhance the development of cross-national reproductive health data systems and data collection; and 3) the challenge of sustainability and continued implementation, and even expansion, of the BMSCP model in the other border sister cities.Several benefits of reproductive health information that go beyond the border region have accrued (or could accrue) from the BMSCP model reproductive health data system. First, Latina reproductive health is relatively understudied in the United States. The BMSCP model, if extended throughout the border region, would provide a major new source of critical and unique information about the reproductive health practices, health care use, and health status of women and infants of Mexican heritage, who made up most of the BMSCP respondents. Information on attitudes about breastfeeding or contraceptive use, for example, could provide valuable insights about Mexican communities far from the border. Moreover, reproductive health information from the Mexican side of the border would allow for an examination of the effect of women's Mexican heritage without the confounding issues of immigration or documentation status.Second, perhaps because BMSCP's principal focus was the common border region, it chose not to focus on migration issues. Many of the women in Matamoros and other border towns are migrants from the interior of Mexico. Meeting the reproductive health needs of highly mobile populations in both Mexico and in the United States is a public health challenge  . The BMSThird, the BMSCP is a unique data set to study acculturation (from the US side) and cultural heritage/retention (from the Mexican side). Issues of acculturation (positive and negative) are at the heart of much recent maternal and child health (MCH) literature on immigrant populations. The BMSCP data revealed that women of Mexican heritage on the US side of the border already show some behavioral differences from their counterparts on the Mexican side of the border; they are less likely to breastfeed and more likely to drink alcohol. US residency appears to have begun to change some reproductive health practices .The Latina birth outcome paradox is that birth outcomes among Latina women in the United States  are comparable to outcomes for US white populations and much better than those in the African American community ,4. TheseSimilarly, from a Mexican national perspective, the retention of cultural heritage can be seen as the inverse of US acculturation. The Mexican government in recent years has taken many steps to extend Mexican citizenship rights beyond its borders . The reproductive well-being and birth traditions of women of Mexican heritage (in any country) should be of concern to the Mexican public health leadership.Additionally, the border region may be its own distinct transnational culture, blending features of both countries into a new hybrid distinct from either Mexican or US mainstream culture. Indeed, cultural blending at borders is often how culture is transformed and transmitted in both directions. The extent to which reproductive health behaviors are blended and transformed at the US-Mexico border is unknown. And although border region culture may be distinct, many women of reproductive age move into it and out of it.Finally, the BMSCP provides a mechanism for comparisons of reproductive health policy between countries. National policies and practices are difficult to assess, but a natural comparison may be right across the US-Mexico border. Information collected uniformly from women of similar cultural heritage on both sides of the border allows for an examination of the effect of national/regional policies. For example, the Mexican government's normative policies expect breastfeeding to commence within 2 hours of birth, with no hospital distribution of formula or other alternatives, which contrasts dramatically with the absence of breastfeeding-friendly policies in the United States. Immediate postbirth breastfeeding rates  reflect these policy differences . On the The BMSCP's methodologic experiences also provided new insights and an innovative model to enhance other reproductive health data systems and data collection methods. First, BMSCP demonstrates that cross-national data collection can be standardized between countries with different data systems and achieve a high level of reliability and utility. Binational cooperation facilitated equivalent dual-language data collection instruments, common training for data collectors, common data collection supervision, and centralized database management.Second, BMSCP showed that a sampling design that used large birthing hospitals could accurately capture the maternal reproductive health experience for all births in the border region. The hospital sample captured 92.7% of Matamoros births and 98.2% of Cameron County births with minimal bias between area registered births and study participant births. Hospitals, especially large hospitals, are now the normative sites for births and can be used to construct high-quality representative sampling frames. Moreover, the BMSCP showed that hospitals would allow and facilitate data collection.Third, BMSCP showed that a questionnaire similar to that used in the US Pregnancy Risk Assessment Monitoring System (PRAMS), a system that samples new mothers via birth certificates and then collects behavioral, medical, and other data from them 2 to 6 months postpartum by mail and telephone, can be systematically and effectively implemented within 1 to 2 days of birth in multiple hospital settings. This timing of BMSCP data collection lessens the "retrospective" duration of most postbirth data collection instruments, shifts the balance of retrospective vs current information collected, and should decrease recall bias, especially for birthing information.Fourth, no birth certificate linkages were required to implement the BMSCP model. This is an advantage in Mexico, where birth registration systems are still developing, and in the United States, where 2 obstacles were avoided: obtaining permission to access confidential data and methodologic issues associated with subsequent data linkage efforts.Fifth, on a practical instrumental level, the BMSCP demonstrated the limits of some questions widely used in US-based survey instruments to classify race or ethnicity, for example, or to accurately self-assess height and weight in this population. BMSCP represents a kind of cognitive testing for survey data items among women of Mexican heritage.Finally, although the BMSCP was conceived as a model of US-Mexico binational border cooperation, the collection of common data may initially be an easier activity than many others for cross-national public health cooperation. It does not require changes in health care system practices to implement. Moreover, it establishes a precedent  to sustain other, more activist interventions and cooperative public health efforts in the future.PCD clearly all want to sustain the BMSCP model and encourage its development in all 14 pairs of border sister cities. The border health community should also embrace and vigorously demand its adoption. The vision exists; the challenge is how to get there from here.The BMSCP was conceived of as a feasibility project, and it proved to be successful and productive. Its real success will be demonstrated, however, only if it is implemented into an ongoing and comprehensive binational surveillance system of border reproductive health . The authors of the BMSCP editorials and articles in this issue of Replication and sustainability require a deliberative plan. A few practical suggestions:Generate political will. Find more advocates in the border health community and beyond.Set up a dedicated advocacy committee.Prepare a mission statement and goals.Be an ongoing visible presence, and keep proposing a binational border reproductive health surveillance system.Encourage an immediate effort to replicate the BMSCP model in 1 more pair of border sister cities. This would start the movement from a demonstration project to translational research. It would provide answers to such questions as the following: Can quality be maintained? Can new local leadership develop? How costly is the project to replicate?Develop a specific implementation plan, and possibly start with less ambitious implementation goals. Start with a limited number of sister cities, and then, like PRAMS, slowly build up to a full complement of all sister cities. Data collection could be implemented every other or every third year. Change is slow, but periodicity is needed to see trends.Consider having a core staff  that can move from 1 site to another to save money in training. Create full-time positions and develop experienced staff.Address the financing issues head on. Cost should not be the principal barrier to further implementation. The BMSCP estimated its cash outlay was $150,000. The real costs are undoubtedly somewhat higher, as it received much in-kind support from CDC, border hospitals, and the Border Health Department, but the cash outlays will still be small. Sister cities could bid on (and fund) their own area reproductive health data collection efforts. Or states could fund all the sister cities on their borders. Mexican states have indicated a willingness to support personnel costs and help with access.Use the data collected by BMSCP in professional publications. The articles presented in this journal are also key to sustainability. Publications extend the value of the BMSCP far beyond the border region. These initial articles are an excellent beginning and hint at the opportunities for further data analysis.I also recommend some revision and augmentation of the content of the current BMSCP questionnaire to better define its data collection niche, to focus more on key reproductive health issues facing the border area, and to increase its appeal to other nonborder constituencies. Specifically:Maternal birthing experiencesOne of the unique features of BMSCP is that it collects data (directly from the mother) right after birth. There is no other ongoing source of information on maternal birthing experiences in the Latina community. The 37% rates of cesarean births on both sides of the border suggest the need for this focus.Women's health over the life courseThe BMSCP could be a source of information on preconception and interconception health and health care. Life-course models are increasingly used to explain reproductive health disparities. Diabetes, hypertension, and obesity are all chronic diseases prevalent in the Latina community, and these conditions often originate in the reproductive years.Migration historyThe BMSCP questionnaire could obtain more or better migration information than other questionnaires, for example, time migrants spend in the border region, the extent of other family migration, attitudes and expectations about migration, nearby family supports, and health and social service needs because of migration.Acculturation/cultural identity/border region identityAs already noted, the BMSCP provides a superb database to study acculturation and cultural identity. It could explore the strength of that identity and help explain the Latina birth outcome paradox.Latina reproductive healthThe BMSCP questionnaire could provide a unique opportunity to examine such topics as theories or hypotheses about Latina social cohesion, attitudes about prenatal care, use of over-the-counter and herbal medicines, and changes in eating habits. This data collection instrument should be directly written to explore Latina health.MCH policy relevanceThe BMSCP survey should strengthen its policy focus. It should start directly with policy questions, compare known variations in national policy and practices, and then examine subsequent reproductive health and health care associations. Noticeably underdeveloped were efforts to evaluate participation in or the effect of reproductive health programs .PCD celebrates the BMSCP demonstration project's success in obtaining and using comparable binational reproductive health data from the border region. The BMSCP, however, should not be only a onetime success story but deserves to be maintained. Ultimately, the project has enhanced our knowledge base to improve the health and well-being of mothers, infants, and families in the border area and throughout the United States and Mexico.This issue of


A key challenge for humanity is how a future global population of 9 billion can all be fed healthily and sustainably. Here, we review how competition for land is influenced by other drivers and pressures, examine land-use change over the past 20 years and consider future changes over the next 40 years.Competition for land, in itself, is not a driver affecting food and farming in the future, but is an emergent property of other drivers and pressures. Modelling studies suggest that future policy decisions in the agriculture, forestry, energy and conservation sectors could have profound effects, with different demands for land to supply multiple ecosystem services usually intensifying competition for land in the future.In addition to policies addressing agriculture and food production, further policies addressing the primary drivers of competition for land  could have significant impacts in reducing competition for land. Technologies for increasing per-area productivity of agricultural land will also be necessary. Key uncertainties in our projections of competition for land in the future relate predominantly to uncertainties in the drivers and pressures within the scenarios, in the models and data used in the projections and in the policy interventions assumed to affect the drivers and pressures in the future. The proc.In addition to agriculture, use is included for forestry, non-food crops and protected areas for biodiversity, as well as use of land for bioenergy and land degradation/restoration. The impact of policy on influencing each of these factors is discussed in §2Land use and cover change synthesis book , particularly the chapter ‘Outlook on agricultural changes and its drivers’, dealing with land-use and land-cover change  for competition are factors of higher causal order that determine the degree of the actual direct pressures The growth in the human population from about 3 billion in 1960 to 6.8 billion in 2010, coupled with increased income and changes in diet, has been accompanied by substantial increases in crop and animal production  has increased from 877 million tonnes in 1961 to 2342 million tonnes in 2007, the world average cereal yield has increased from 1.35 t ha in 2007 . Put anoThere have also been substantial changes in human food consumption reflected in dietary and nutritional changes over recent decades . There i(b)While agricultural production for food consumption is one of the predominant land-use activities across the globe, land is also used for the production of timber, fibre, energy and landscape amenities as well as being consumed by urbanization.(i)Historically, the production of forest products has grown rapidly—and again, in the future a further increase is necessary The growth of crops for bioenergy has been highlighted as a potential competitor for land with food crops. It is noteworthy, though, that the area occupied by bioenergy and its by-products in 2004 was only 14 Mha compared with 1500 Mha of crops  and 4500 Mha of pastures worldwide . While t(iii)An increasing trend in some parts of the world is the use of land for amenity activities and/or biological conservation. This includes recreational uses such as public parks, golf courses and other sports facilities, as well as the conservation of traditional landscapes for their aesthetic, cultural or natural heritage value. Land competition between amenity and other uses depends strongly on geographical location, with stronger pressures for amenity use occurring on land near to urban centres. However, many cultural landscapes are multi-functional, being used, for example, for food or timber production, as well as offering amenity services. Setting aside land for amenity or conservation potentially increases competition for land on the remaining area, which we return to in §§4 and 5.(c)Degradation of soil and land through inappropriate use or the addition of pollutants has been a topic of concern for many decades, because of the potential impact on biodiversity, and the availability of land for the human population to feed itself. Degradation of land intensifies competition for land, since it reduces the quantity of land suitable for a range of uses such as food production. Agriculture almost always results in stresses being applied to land , but the properties of some soils allow them to recover naturally and rapidly, while others may require amendments (e.g. inputs of fertilizer) or other physical interventions to regain their productive ability . By redu(d)Agricultural policy in many developed countries is dominated by protectionism, established through trade tariffs and producer support (subsidies). Subsidies affect land-use decisions by influencing the types of land-use strategies adopted by a land manager. So, for example, farmers will only grow crops for which they receive financial support through direct payment. In this sense, subsidies tend to limit competition for land. Subsidies also distort markets on a global scale and influence the competitiveness of agricultural land use in other regions of the world. Conversely, policy liberalization often leads to land-use diversification as seen, for example, in New Zealand following the 1984 agricultural policy reforms , which ostatus quo of traditional agricultural landscapes, such policies limit or remove entirely the competition between alternative land uses. Other policies such as the European agri-environment schemes compensate farmers for managing their land to high environmental protection standards. The common theme in rural development and environmental protection policies, however, is the support of farmer incomes, and this leads to the maintenance of current land-use practices that limits land competition.Pressure from the World Trade Organization, among other drivers, has in part led the governments of the developed world to move away from production-related support to new policy directions based on rural development or environmental protection. Policies such as the Less Favoured Area scheme in Europe, for example, were designed with the objective of protecting agricultural land use in areas with a competitive disadvantage, usually because of physical limitations such as topography or climate. By preserving the per se, but is also important in considering the wider concept of competition for ecosystem services.Competition for land is associated with deforestation owing to agricultural expansion while, at the same time, expansion of forests is leading to competition with other land uses. Furthermore, permanent forest clearing is associated with the loss of many other ecosystem services. Thus, deforestation is not only a phenomenon of competition for land 3.Since 1960, agricultural area has increased from just under 4.5 billion ha to just over 4.9 billion ha in 2007 . During As described in §2, the close to tripling of global food production since 1960 has largely been met through increased food production per unit area. For example, Box 1.The IMAGE Integrated Assessment Model  is a modThe macro-economic EPPA model was developed to examine climate and energy policy applications. Future scenarios are driven by economic growth using the GTAP data as base information, simulating the economy recursively at 5-year intervals. Five land types are considered to be interchangeable without restrictions, as long as conversion costs are met . Reversion to the natural state occurs under no costs, with any prior investment being fully depreciated.The MiniCAM model is also an environmental integrated assessment model. Land is allocated between different categories according to its expected profitability. This is determined by the productivity of the respective product, product price, the rental rate of the land and the non-land cost of production. Managed and unmanaged ecosystems are interchangeable according to the above.Quickscan is a spreadsheet-based model constructed to analyse the bioenergy potential under consideration of key drivers and correlations. The study considered here identified the consumption of animal products as a key factor for agriculture land use and examined alternative production systems. The resulting spared land is considered to be available for bioenergy production. Therefore, the study considered only had the land categories ‘bioenergy’ and ‘pasture’.The GRAPE model is a macro-economic model of climate change. Land is allocated according to food demand of the population and the land-use rent that takes carbon costs  into account.2 mitigation via forest-sink enhancement are based on the sensitivity analysis of the DIMA model, the AEZ-BLS framework provides inputs with respect to agricultural land expansion.For the MESSAGE-MACRO framework, integration of agriculture and forestry sectors has been achieved through linkages to the DIMA and AEZ-BLS models as described in GLOBIOM integrates the agricultural, bioenergy and forestry sectors. Changes in the demand on the one side and profitability of the different land-based activities on the other side are the major determinants of land-use change. Spatially explicit land-use suitability and respective productivities, as well as environmental effects, are taken into account The previous sections have shown that land-use changes are a result of the interaction of a variety of drivers and pressures. In particular, population growth and a shift towards more meat-intensive diets have in the past contributed to an increasing demand for agricultural land. These factors are expected to continue to be important in the future, although trends will differ in time and across regions. Historically, the demand for more agricultural production has been partly compensated by technological advances, and improving technology will determine whether yields will continue to improve in the future.The complexity of the interactions between different drivers necessitates the use of scenario studies using models of land resources and land use, to analyse the consequences of particular trends and policies. There is a variety of studies and a range of models for addressing these issues. Box 1 gives an overview of the most commonly used models for such analysis at the global scale. For a review of land-use change scenarios at the regional scale, see Future land-use trends are described as part of studies that look into long-term agriculture trends (such as the projections published by the Food and Agriculture Organization of the United Nations (FAO) and International Food Production Research Institute (IFPRI). In addition, studies focusing on agricultural trade increasingly tend to describe the relationships between trade flows and land use. Finally, integrated assessment models, used for examining global environmental change and climate change, are increasingly applied to investigate how climate policies might interact with land-use change. The type of models used in these different areas vary greatly, ranging from models derived from the economic tradition  to partial agricultural-economy models (like IMPACT), and models that focus mostly on the interaction of economic activity and biophysical indicators . General equilibrium models account for the economic linkages of the land-use sector with the rest of the economy and allow for assessment of income generation owing to land-use activities. Another strength of these models is their consistent description of agriculture trade. Partial equilibrium models allow for detailed study of agricultural production of different crops and within different regions. Moreover, some of these models are also able to represent specific land-use-related policies. Biophysically based models allow the relationship between environmental parameters , land use and agriculture to be studied. Within the scope of this paper, we will not be able to review the complete literature of land-use scenarios; instead we will focus on a few noteworthy projections , while i(i)The most widely used agricultural projections are those of FAO and IFPRI. IFPRI uses the IMPACT model as the basis of its projections. The methods underlying the FAO projections are more diverse, utilizing both models and expert consultations. Both studies consider mostly agricultural markets, and thus do not fully cover land-use projections. The scenario projections in the Global Environmental Outlook-4 , the Mil(ii)a). The increase in production is somewhat slower than in the past, as a result of a slowdown in population growth. Diets are projected to become more meat-intensive, with annual per capita meat consumption increasing. The growth in production of cereals over the 2000–2050 period, based on a range of assessments, varies between 43 and 60 per cent The actual demand for cropland in the future depends on the balance between increases in agricultural demand and increases in yield improvement. Historically, yield improvements (approx. 80%) have been more important in increasing production than expansion of agricultural land . As a result, agricultural areas have expanded by about 5 per cent since 1970. Scenarios show a very large variation in the expected development in cropland figures –6. The 2The slightly lower contribution (on average) from the expansion of crop area can be attributed to increasing land scarcity and reduced growth of the global population. The decreasing quality of land brought into production, however, may mean that a greater percentage of gains in total production will need to be found from crop area expansion than has historically been the case (as indicated in (iv)Increases in meat production will occur through a number of means, including changes that lead to intensified production systems, such as more efficient conversion of feed into animal products, and via expansion of land use for livestock . PreviouFor grazing land, the range of 2050 scenario projections ranges between a 5 per cent contraction to a 25 per cent increase . Most studies show an increase of 10 per cent or less. The IAASTD baseline, for instance, projects an almost constant grazing area ((v)Obviously, the total demand for agricultural area arises from trends in cropland and grassland. Studies show diverging trends , but theAn important implication, however, is further loss of the area available for unmanaged ecosystems. This is already shown in Ever-increasing competition for land may endanger the integrity of currently protected areas, which are located and classified in the World Database on Protected Areas . Most mo5.Uncertainties in projecting land use have a range of sources, including the level of understanding of the underlying causal relationships , the degree of complexity of underpinning system's dynamics , the degree of path dependency (i.e. ‘to what degree does the current system state and past trends determine future developments?’), the level of uncertainty introduced by the time horizon (i.e. ‘how far into the future?’) or even surprises and unpredictable future developments. Some of these phenomena follow known random processes while others cannot be explored well enough as we lack anticipative capacity. For a more complete discussion of different types of uncertainties and their consequences for methods to explore the future, see This section serves to illustrate some of these uncertainties inherent in future projections of land use and of competition for land, and how these are critically dependent upon future policies on forest protection and bioenergy supply, and future trends in agricultural product preferences and consumption.Given that there is substantial uncertainty about how different drivers will evolve and how they will impact upon the competition for land, here we illustrate the impact of uncertainty by presenting results of eight selected changes of drivers between 2020 and 2030. The analysis presented here was carried out using the GLOBIOM model . To asseThe scenarios were defined in such a way that any expansion of cropland would occur at the cost of forest land in order to have a ‘pure’ measure of the degree of competition for land. Under this scenario specification, the GLOBIOM model considers only drivers of deforestation coming from agriculture or bioenergy production. We consider that the model operates under the constraint of a fixed total land area, and allocates land use according to the economic competitiveness of different land-use activities. Deforestation is used as a measure of the degree of competition for land and is itself costly. The cost of avoiding deforestation is equal to the difference between the cost of deforestation itself and the income from agricultural production that would occur on that land subsequently if it were deforested and used for agriculture (opportunity cost). Under avoided deforestation, the degree of competition for land is mitigated at the cost of land-use intensification and reduced consumption  could have significant impacts in reducing competition for land. Technologies for increasing per-area productivity of agricultural land will also be necessary. Key uncertainties in our projections of competition for land in the future relate predominantly to uncertainties in the drivers and pressures within the scenarios, uncertainties in the models and data used in the projections and the policy interventions assumed to affect the drivers and pressures in the future. Though price has been used as an indicator of land scarcity and, therefore, competition for land, the development of other indicators to assess the intensity for competition for land is in its infancy, and the development of new metrics will advance our understanding of competition for land in the future.