Use of β-Blocker in pregnancy and risk of fetal cardiac anomalies.

The use of β-Blocker in pregnancy does not increase the risk of fetal congenital cardiac anomalies after adjusting for maternal co-morbidities says the results of a large population basedcohort study conducted by department of research and evaluation at Kaiser Permanente Southern California.

The study was reported as a research letter online April 17, 2017 in JAMA Internal Medicine.

Lewei Duan and colleagues from Kaiser Permanente, California note, “Beta-blockers are the most commonly used class of medication for treating cardiac conditions in pregnant women. Despite the common use of this class of medication, data that support its safety are limited.”

“A recent meta-analysis reported an association between beta-blocker exposure and fetal congenital cardiovascular defects, raising a concern regarding potential teratogenic effects of this class of medication.”

The authors identified 379,238 women through birth records who delivered at Kaiser Permanente, Southern California through a period of 11 years (2003-2014). Of these, 4847 women (1.3%) received β-Blocker during pregnancy as identified by pharmacy dispensing records.

And, 2,628 (0.7%) were exposed during the first trimester of pregnancy.

Most common beta-blockers were labetalol (n = 3357), atenolol (n = 638), propranolol (n = 489) and metoprolol (n = 324). The most common indication for prescribing beta-blockers was hypertension.

Data analysis revealed that women on beta-blockers were older and had higher body mass index(BMI). They also had higher prevalence of chronic comorbidities like hyperlipidemia, diabetes, hypertension, heart failure, a history of arrhythmia and pregnancy complications like preeclampsia and eclampsia.

They also delivered about a week early than those not taking beta-blockers (mean 37.4 weeks vs. 38.9 weeks).

In unadjusted analyses, women on beta-blockers were significantly more likely to have a baby with congenital cardiac malformation as compared to those not taking the drug (P < 0.001).

When after taking into account the confounders like maternal age, BMI, and comorbidities and gestational age at delivery, there was no longer any association between the exposure and the outcome (P = 0.32).

This suggests that the association seen in unadjusted analyses was caused by maternal demographics and other chronic co-morbidities and not due to beta-blockers.

“The previously reported association between beta-blocker use and fetal cardiac anomalies in other studies may be attributed to confounding,” Duan and colleagues concluded. “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.”

Access the Abstract here 

Primary source: Duan L, Ng A, Chen W, Spencer HT, Nguyen J, Shen AY, Lee M. β-Blocker Exposure in Pregnancy and Risk of Fetal Cardiac Anomalies. JAMA Intern Med. 2017;177(6):885-887. doi:10.1001/jamainternmed.2017.0608