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 text of chi2 analysis) with that of a control group matched for maternal age and smoking.

RESULTS: There was no increase in major malformation (2/66=3.0% [calcium channel blockers] vs 0% [nonteratogenic controls], p=0.27); a fivefold increase was ruled out (baseline 2%, alpha = 0.05, beta = 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 -334 gm vs nonteratogenic controls, p=0.08).

CONCLUSION: This study suggests that calcium channel blockers do not represent a major teratogenic risk.