Medline ® Abstracts for References 44,45

The technique of meta-analysis was used to derive typical estimates of the risk of congenital malformations from oral contraceptive (OC) exposure in early pregnancy. Several definitions were used for non-exposure to reduce bias from this source. Congenital heart defects and limb reduction defects were analyzed separately. The typical relative risk from the 12 prospective studies analyzed was 0.99 (95% confidence interval 0.83, 1.19) for all malformations. The definition of non-exposure did not materially change this estimate. The typical risk for congenital heart defects was 1.06 (95% confidence interval 0.72, 1.56) and for limb reduction defects, 1.04 (95% confidence interval 0.30, 3.55). This lack of an association between OCs and birth defects in prospective studies agrees with the results of most of the better-designed case-control studies.

Intrauterine exposure to artificial sex hormones such as oral contraceptives may be associated with an increased risk of fetal death. Between 1996 and 2002, a total of 92 719 women were recruited to The Danish National Birth Cohort and interviewed about exposures during pregnancy. Outcome of pregnancy was identified through linkage to the Civil Registration System and the National Discharge Registry. The authors analysed the risk of fetal death after recruitment to the cohort by using proportional hazards regression models with gestational age as the underlying time scale. In total, 1102 (1.2%) women took oral contraceptives during pregnancy. Use of combined oestrogen and progesterone oral contraceptives (COC) or progesterone-only oral contraceptives (POC) during pregnancy was not associated with increased hazard ratios of fetal death compared with non-users, HR 1.01 [95% CI 0.71, 1.45]and HR 1.37 [95% CI 0.65, 2.89]respectively. Neither use of COC nor POC prior to pregnancy was associated with fetal death. Stratification by maternal age and smoking showed elevated risks of fetal death for women<30 years and smokers using oral contraception during pregnancy, but the interactions were not significant. In conclusion, there was no evidence that oral contraceptive use before or during pregnancy is associated with an increased risk of fetal death.