A new study has found that the two most commonly prescribed antibiotics are not associated with an increased risk of adverse outcomes in pregnant women. 

Researchers from the University of Montreal evaluated macrolide antibiotics to determine whether the infections or the macrolides themselves placed women and their unborn babies at greater risk of adverse pregnancy outcome, such as birth defects. They set out to estimate the risk of major congenital malformations after fetal exposure to the two most commonly used macrolides. 

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The study team used data held in the Quebec Pregnancy Cohort that details medical information on hundreds of thousands of pregnancies along with mother and newborn outcomes. Data on the mother’s use of azithromycin and clarithromycin was obtained from Quebec’s public pharmaceutical insurance program and compared to penicillin use. 

A total of 135,839 pregnancies were included in the study, of which 1.7% involved exposure to macrolides during the 1st trimester with 9.8% of pregnancies resulting in child having a major congenital malformation. After adjusting for potential confounders, the analysis showed azithromycin, erythromycin, and clarithromycin use during the 1st trimester of pregnancy were not statistically significantly associated with the risk of major congenital malformations, and no associations were seen for cardiac malformations.  

Researchers concluded that “wider studies will need to be undertaken in order to confirm the safety of less-often prescribed antibiotics.” 

For more information visit onlinelibrary.wiley.com.