Future developments in assisted reproduction in XXXX .

@entity1 @entity2208 @entity2007 @entity4810 @entity5 @entity74 @entity52
The advent of @entity1 @entity52 ( @entity52 ) over 30 years ago has made the oocyte and preimplantation embryo uniquely accessible. This accessibility has given rise to new micromanipulation techniques, such as intracytoplasmic sperm injection for treatment of @entity4810 , as well as embryo biopsy for preimplantation diagnosis of both @entity74 and @entity2007 , a major cause of early embryo demise and @entity2208 . In the UK, average pregnancy rates after @entity52 and embryo transfer are < 25%, even after transfer of several embryos. Unfortunately, a third of these pregnancies involve multiple gestations. Research is currently focusing on methods to improve @entity52 success rates while reducing twin and triplet pregnancies and their associated increased morbidity and mortality. One approach is to develop screening methods to identify the most viable embryos, so that transfer of fewer healthy embryos will result in a higher proportion of singleton pregnancies. Screening methods include optimizing culture conditions for prolonged culture and selection of viable blastocysts for transfer, or embryo biopsy and @entity2007 screening. Assisted reproduction is also increasingly important in other branches of medicine: survival rates for @entity5 sufferers are improving continually and there is now a significant need for approaches to preserve fertility after sterilizing chemo-and radiotherapy treatment. Techniques for cryopreserving male and female gametes or gonadal tissue are being developed, although systems to grow and mature these gametes are in their infancy. Finally, there are also concerns regarding the safety of these new assisted reproductive technologies.
