Are macrolides a risk in pregnancy?

In early 2020, the British Medical Journal (BMJ) urged caution regarding the use of some antibiotics in pregnancy. A study they published had found that children of mothers prescribed macrolide antibiotics during early pregnancy were at an increased risk of major birth defects, namely heart defects, when compared with children of mothers who received penicillin. The researchers therefore stated at the time that this meant macrolides should be used with caution throughout pregnancy and if appropriate alternative options can be prescribed, that would be best until further research is able to give more evidence as to the apparent risk macrolides present.

Macrolide antibiotics include erythromycin, clarithromycin and azithromycin, and are often used to treat common bacterial infections, particularly as an alternative for patients with penicillin allergy. The BMJ (2020) did state that research in the past suggested evidence of rare yet serious adverse outcomes of macrolide use, particularly in unborn babies.

In order to address the uncertainties surrounding macrolide use, a team of researchers at UCL carried out research to analyse the association between macrolide antibiotics prescribed during pregnancy and major malformations, as well as four neurodevelopmental disorders (cerebral palsy, epilepsy, ADHD, and autism spectrum disorder) in children.