Childbearing and the risk of XXXX .

@entity1 @entity978 @entity5
The causes of @entity978 remain incompletely known, but a higher incidence in @entity1 than in @entity1 has prompted an interest in the role of female sex hormones and reproductive history. Available epidemiological data are, however, contradictory. We analyzed possible associations between parity, age at first birth, and the risk of developing @entity978 by a linkage between the Swedish @entity5 Register and a nationwide Fertility Register. Among @entity1 born between 1925 and 1972, 917 cases with @entity978 and concomitant fertility information were identified. For each case @entity1 , five age-matched controls were randomly selected among @entity1 in the Fertility Register. Conditional logistic regression was used to estimate odds ratios of @entity978 associated with a birth. We found a slightly and nonsignificantly reduced risk of @entity978 in ever-parous compared with nulliparous @entity1 . Among parous @entity1 , the number of @entity1 was unrelated to risk, whereas there was some evidence of an increased risk with late age at first birth in @entity1 under age 45 at diagnosis. No clear temporal relations between childbearing and subsequent risk were discernible in any parity or age group. Although uncontrolled confounding might have affected our results, they do not indicate that hormonal or immunological changes associated with childbearing play a role in the development of @entity978 .
