The authors conducted a case-control study of the relation of OC use after conception to the occurrence of congenital urinary tract anomalies (CUTAs). Singleton CUTA cases with no known chromosomal abnormality from seven counties in western Washington State born during the period January 1, 1990-December 31, 1991 were identified through the Washington State Birth Defect Registry. Controls without birth defects were randomly selected from singleton births that occurred in the same year as the cases in five large hospitals in King County. Mothers of the 118 cases and 369 controls were interviewed to obtain their contraceptive history as well as other information. Mothers of nine cases (7.6%) and eight controls (2.2%) had taken OCs at some time during the pregnancy. After adjustment for birth year and county of maternal residence, OC use after conception was associated with an almost five-fold increased risk of having a baby with a CUTA [odds ratio (OR) = 4.8, 95 percent confidence interval (CI), 1.6-14.1] relative to no contraception at or after conception. Use of other contraceptive methods after conception was not related to the risk of CUTAs. OC use during the 3 or 6 months prior to the conception also was not associated with the risk of CUTAs. Further adjustment for sociodemographic factors, reproductive history, perinatal exposure to exogenous agents, and past OC use did not change the results, nor did restricting the analysis to residents of King County.(ABSTRACT TRUNCATED AT 250 WORDS)
PIP: A case-control study examined the relation of OC use after conception to the occurrence of congenital urinary tract anomalies (CUTAs). Singleton CUTA cases with no known chromosomal abnormality from 7 counties in western Washington state born during the period January 1, 1990-December 31, 1991 were identified through the Washington State Birth Defect Registry. Controls without birth defects were randomly selected from singleton births that occurred in the same year as the cases in 5 large hospitals in King County. Mothers of the 118 cases and 369 controls were interviewed to obtain their contraceptive history. Mothers of 9 cases (7.6%) and 8 controls (2.2%) had taken OCs at some time during the pregnancy. After adjustment for birth year and county of maternal residence, OC use after conception was associated with a 4.8-fold increased risk of having a baby with a CUTA [odds ratio (OR) = 4.8, 95% confidence interval (CI), 1.6-14.1) relative to no contraception at or after conception. The risk seemed to increase with increasing duration of OC use after their last menstruation: OR = 8.0 for women with longer than 4 weeks duration of use. Use of other contraceptive methods after conception was not related to the risk of CUTAs. OC use during the 3-6 months prior to conception was not associated with an increased risk of CUTAs in offspring relative to no OC use during the same period. Further adjustment for sociodemographic factors, reproductive history, perinatal exposure to exogenous agents, and past OC use did not change the results, nor did restricting the analysis to residents of King County. The cases exposed to prenatal OC use were slightly more likely to have megaloureter than were unexposed cases (4/9 vs. 27/109). These results are compatible with the hypothesis that oral contraceptive use after conception predisposes to the development of CUTAs in offspring; this hypothesis should be tested in other epidemiological studies of congenital malformations.