ORAL-CONTRACEPTIVES AND OVULATORY CAUSES OF DELAYED FERTILITY

The return of fertility for women who discontinue oral contraceptives takes longer as compared with women who discontinue other methods of c ontraception. It remains unclear, however, whether subsequent fertilit y differs according to duration or age at first use, The authors perfo rmed a nested case-control study within a cohort of 116,686 female reg istered nurses residing in 14 US states, Baseline information was repo rted on mailed questionnaires in 1989, Cases comprised 1,917 married n urses without previous pregnancy who were unable to become pregnant fo r at least 1 year and were subsequently diagnosed with primary ovulato ry infertility, Controls comprised 44,521 married parous nurses with n o history of infertility and no pregnancies lasting less than 6 months . After allowing for 2 years of suppressed fertility following discont inuation of oral contraceptive use and excluding women with signs of m enstrual or hormonal disorder, the authors found that the multivariate relative risk for ovulatory causes of delayed Fertility was 1,2 (95% confidence interval 0.7-1.9) for ever users, There was no statisticall y significant trend of increasing risk with increasing duration of use and younger age at first use, The fact that 88 percent of cases repor ted an eventual pregnancy by 1993 suggests that absolute fertility was not impaired.