The safety of calcium channel blockers in human pregnancy: A prospective, multicenter cohort study

OBJECTIVE: Our purpose was to examine the potential teratogenicity of calcium channel blockers. STUDY DESIGN: Six teratogen information services prospectively collected and followed up 78 women with first-trimester exposure to calcium channel blockers. Pregnancy outcome was compared (by paired t test or χ² analysis) with that of a control group matched for maternal age and smoking. RESULTS: There was no increase in major malformations (2/66 = 3.0% [calcium channel blockers] vs 0% [nonteratogenic controls], p = 0.27); a fivefold increase was ruled out (baseline 2%, α = 0.05, β = 0.20). The defects reported were attributable to maternal diabetes or coingestion of teratogens. The increase in preterm delivery (28% [calcium channel blockers] vs 9% [nonteratogenic controls], p = 0.003), attributed to maternal disease by stepwise regression, was the most important factor responsible for the observed decrease in birth weight (mean 384 gm vs nonteratogenic controls, p = 0.08). CONCLUSION: This study suggests that calcium channel blockers do not represent a major teratogenic risk.