Antihypertensive drugs and the risk of congenital anomalies.

Study Objective: To estimate the prevalence of congenital anomalies among the offspring of women exposed and unexposed to antihypertensive drugs during early pregnancy.

Design: Matched cohort study.

Database: The United Kingdom's General Practice Research Database.

Subjects: Women exposed to antihypertensive drugs during early pregnancy and a sample of matched unexposed pregnant women.

Measurements And Main Results: The prevalence of any anomaly among unexposed and exposed women was 23.5 (95% confidence interval [CI] 14.4-38.3) and 20.9 (95% CI 10.0-43.8) per 1000 pregnancies, respectively (relative risk [RR] 0.9, 95% CI 0.4-2.2). The relative risk of limb anomalies among women exposed to β-blockers was 6.4 (95% CI 0.6-70.1). Exposure to angiotensin-converting enzyme (ACE) inhibitors, β-blockers, and calcium channel blockers increased the risk of genital anomalies (RR 3.8, 95% CI 0.9-16.0; RR 2.8, 95% CI 0.7-11.9; RR 1.3, 95% CI 0.1-12.4, respectively).

Conclusion: ACE inhibitors prescribed in the first trimester of pregnancy appeared to increase the risk of congenital anomalies among the offspring of exposed women (RR 2.5, 95% CI 0.5-13.5). These drugs should be avoided in women planning to become pregnant. A marginally increased risk was also found with exposure to β-blockers (RR 1.4, 95% CI 0.6-3.3). These findings are based on small numbers and are not statistically significant.