A cohort study of reproductive factors and family history of XXXX in southern Sweden.

@entity1 @entity5 @entity0
BACKGROUND: Studies have been contradictory regarding the hypothesis that reproductive risk factors of @entity0 as parity and age at first full-term pregnancy (AFFP) operate differently in @entity1 with and without a family history of @entity0 . METHODS: The overall @entity5 incidence and @entity0 incidence related to fertility factors were followed in a population based cohort of 29,508 @entity1 aged 25-65 when interviewed between 1990 and 1992 in south Sweden. At the end of the follow up in December 1999, the cohort constituted 226,611 @entity1 years. The risk of @entity0 in relation to reproductive factors were studied in @entity1 with at least one first degree relative with @entity0 and compared with @entity1 without a family history. FINDINGS: A total of 1145 @entity5 were seen and 1166.6 were expected (SIR = 0.98, 95% CI = 0.93-1.04). Slightly more @entity0 cases were seen 434 than expected 387.69 (SIR = 1.12, 95% CI = 1.02-1.23). A family history of @entity0 among a first degree relative was present in 1615 @entity1 . Forty-five @entity0 were seen among these @entity1 while 24.27 was expectecd (SIR = 1.85, 95% CI = 1.35-2.48). Nulliparous @entity1 with a family history of @entity0 had a higher risk of @entity0 , SIR = 1.76, 95% CI = 0.64-3.82, compared with nulliparous @entity1 without a family history, SIR = 1.13, 95% CI = 0.99-1.29. Similarly @entity1 with parity 1-2 with a family history had a higher SIR = 1.81, 95% CI = 1.16-2.69 compared with @entity1 without a family history having 1-2 @entity1 , SIR = 1.13, 95% CI = 0.99-1.29. In @entity1 with > or = 3 @entity1 those with a family history continued to have a high SIR = 1.98, 95% CI = 1.11-3.27 compared with @entity1 without a family history SIR = 0.90, 95% CI = 0.73-1.09. An early full-term pregnancy was protective in both groups. A higher risk than nulliparous @entity1 were seen after age 25 in the family history group and after age 30 in the @entity5 group. INTERPRETATION: @entity1 with a first degree family history of @entity0 do not experience the sameprotection from a high number of pregnancies as @entity1 without a family history. However, an early first full-term pregnancy seems to offer a substantial protection in the family history group if undertaken before age 20. This suggest that reproductive factors tend to operate differently in the two groups of @entity1 .
