After adjusting for maternal comorbidities, women who received beta-blockers during pregnancy did not have an increased risk of fetal congenital cardiac anomalies, according to a retrospective, population-based cohort study.

Lead researcher Lewei Duan, MS, of Kaiser Permanente Southern California, and colleagues published their results online in JAMA Internal Medicine on April 17.

Pregnant women often are prescribed beta-blockers to treat cardiac conditions, although the researchers mentioned safety data are limited. They added that a meta-analysis published in 2013 found an association between beta-blocker exposure and fetal congenital cardiovascular defects.

For this analysis, the researchers identified 379,238 births in the Kaiser Permanente Southern California region between Jan. 1, 2003 and Dec. 31, 2014.

They added that 1.3 percent of pregnant women were exposed to beta-blockers, including 0.7 percent during the first trimester of pregnancy. The most commonly prescribed beta-blockers were labetalol, atenolol, propranolol and metoprolol.

Women who were prescribed beta-blockers were significantly older, had a significantly higher body mass index and were significantly more likely to have hypertension, hyperlipidemia, diabetes, congestive heart failure, arrhythmia, chronic kidney disease, preeclampsia and eclampsia. They also had a significantly lower gestational age at delivery.

The researchers found that cardiac anomalies occurred in 1.9 percent of women who did not receive beta-blockers, 5.1 percent of women who received beta-blockers anytime during pregnancy and 4.9 percent of women who received beta-blockers during the first trimester of pregnancy. The cardiac anomalies included atrial septal defect, patent ductus arteriosus, conotruncal defects, single ventricle physiology, ventricular septal defect and coarctation.

Although unadjusted analyses indicated that beta-blocker exposure was associated with significantly increased odds of fetal congenital cardiac abnormalities, there was no longer an association when the researchers adjusted for maternal age, gestational age at delivery, white race, body mass index and comorbidities. The comorbidities were hypertension, hyperlipidemia, diabetes, congenital heart disease, heart failure, coronary artery disease, stroke, arrhythmia and chronic kidney disease.

“These results suggest that the associations seen in the unadjusted analysis were caused by confounders rather than effects conferred by [beta-blocker] exposure itself,” the researchers wrote.

The researchers mentioned the study had a few limitations, including that they relied on pharmacy dispensing information to estimate beta-blocker exposure. They also could not determine if the pregnant women took the medication. However, they said that using pharmacy dispensing information allowed them to avoid recall bias that could arise in studies that use surveys to determine medication exposure.

“While these findings do not definitively rule out the possibility of fetal congenital defects in association with [beta-blocker] use, these results do provide reassurance regarding the use of this class of medication for the treatment of cardiac conditions in pregnant women,” the researchers wrote.