Safety of Macrolides During Pregnancy

Objective: Prior studies have reported increased risks of congenital heart defects (CHD) and pyloric stenosis (PS) after prenatal exposure to macrolide antibiotics. We sought to assess the association between maternal use of erythromycin and nonerythromycin macrolides and the risks of CHD and PS.

Study Design: Among participants in the Slone Epidemiology Center Birth Defects Study from 1994 through 2008, we identified 4132 infants with CHD and 735 with PS as cases, and 6952 infants without any malformation as controls. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) associated with use of erythromycin or nonerythromycin macrolides in each trimester using conditional logistic regression and adjusting for risk factors for CHD and PS, fever, specific types of infections, and their associated treatments.

Results: During the first trimester, 0.4% and 0.7% of control women had used erythromycin and nonerythromycin macrolides, respectively. Compared to non-use during pregnancy, first-trimester exposure to erythromycin was not associated with an increased risk of CHD (OR, 1.3; 95% CI, 0.6-2.6) or PS (OR, 0.9; 95% CI, 0.3-3.0). The corresponding ORs for nonerythromycin macrolides were 0.7 (95% CI, 0.4-1.3) for CHD and 1.7 (95% CI, 0.6-4.6) for PS. We found no association between third-trimester exposure to erythromycin or nonerythromycin macrolides and the risk of PS. Hypothesis generation analyses did not identify appreciable associations between maternal use of macrolides and other common specific birth defects.

Conclusion: We found no meaningful associations between the risks of CHD, PS, and other common malformations in relation to use of macrolides in pregnancy.