Risks of congenital malformations and perinatal events among infants exposed to calcium channel and beta-blockers during pregnancy

Purpose Calcium channel blockers and beta-blockers (BBs) are widely used during pregnancy, but data on their safety for the developing infant are scarce. We used population-based data from 5 HMOs to study risks for perinatal complications and congenital defects among infants exposed in-utero. Methods We studied women older than 15 years delivering an infant between 1/1/96 and 12/31/00, who had been continuously enrolled with prescription drug coverage for >= 1 year prior to delivery. Information on prescription drug dispensings, inpatient, and outpatient diagnoses and procedures was obtained from automated databases at each HMO. Results There were 584 full-term infants exposed during pregnancy to BBs and 804 full-term infants exposed to calcium-channel blockers, and over 75 000 unexposed mother infant pairs with >= 30 days follow-up. Infants exposed to BBs in the third trimester of pregnancy had over threefold increased risk for hypoglycemia (RR 3.1; 95% CI 2.2, 4.2) and an approximately twofold increased risk for feeding problems (RR 1.8; 95% CI 1.3, 2.5). Infants exposed to calcium-channel blockers in the third trimester had an increased risk for seizures (RR 3.6 95% CI 1.3, 10.4). Chart review confirmed the majority of the exposed seizure and hypoglycemia cases. There were no increased risks for congenital anomalies among either group of infants, except for the category of upper alimentary tract anomalies; this increased risk was based on only two exposed cases. Conclusions Infants whose mothers receive BBs are at increased risk for neonatal hypoglycemia, while those whose mothers take calcium-channel blockers are at increased risk for neonatal seizures. Copyright (C) 2010 John Wiley & Sons, Ltd.