The safety of calcium channel blockers during pregnancy: a prospective, multicenter, observational study.

OBJECTIVE: To assess the safety of calcium channel blockers during the first trimester of pregnancy. STUDY DESIGN: A multicenter (n=11), prospective observational study of the European Network of Teratology Information Services (ENTIS). The rate of major birth defects was compared between a cohort of pregnant women exposed to calcium channel blockers during the first trimester (n=299) and a control group not exposed to potential teratogens (n=806). RESULTS: Major birth defects were not more common in the study group than in the control group. Birth weight was significantly lower in exposed term newborns. There were more preterm infants in the study group than in the control group (23.8% vs. 6.5%). These adverse effects are more likely due to the underlying disease than to the medication. CONCLUSION: This study suggests that calcium channel blockers during the first trimester of pregnancy do not represent a major teratogenic risk.