Context

Infantile hypertrophic pyloric stenosis (IHPS) is a potentially life-threatening condition for which surgical treatment yields excellent patient outcomes.1 However, the aetiology of IHPS remains elusive. Prior studies have implicated early neonatal exposure to erythromycin as a strong risk factor for IHPS, but it is less clear whether maternal use in late pregnancy or while breastfeeding also poses a risk.2 Perinatal exposure to macrolide antibiotics is not uncommon. About 1% of pregnant women report use in the third trimester, and while no macrolides are licensed by the US Food and Drug Administration for use in infants less …