Macrolides vs penicillin and potential risk during pregnancy

There has been some debate about whether particular antibiotics present a risk when used in pregnancy. In early 2020, a study published in the British Medical Journal (BMJ, 2020) found that children of mothers who were 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.

Macrolide antibiotics include erythromycin, clarithromycin, and azithromycin, and are often used to treat common bacterial infections, particularly as an alternative for patients with allergies to penicillin.

The BMJ (2020) noted that their study findings meant that macrolides should be used with caution throughout pregnancy and that it would be best where possible to prescribe appropriate alternative options until further research provides further evidence regarding the apparent risk presented by macrolides. The authors stated at the time that past research suggested evidence of rare yet serious adverse outcomes of macrolide use, particularly in unborn babies. These outcomes were also found mainly to consist of heart rhythm problems, but the BMJ commented that policy advice at the time about macrolide use in pregnancy was variable (BMJ, 2020).