LAUSR

BACKGROUND Pregnant individuals are likely to need antibiotics during the peripartum period. For pregnant individuals who report a history of penicillin allergy, non-beta-lactam antibiotics are often administered. Compared to first-line beta-lactam antibiotics, alternative antibiotics can be less effective, more toxic, and more costly. It remains unclear if being labelled with a penicillin allergy is associated with adverse maternal and neonatal outcomes. METHODS We conducted a retrospective cohort study of all pregnant patients who delivered a viable singleton between 24-42 weeks of gestation at a large academic hospital from 2013-2021. We compared patients who had a documented penicillin allergy history in their electronic medical record versus those who did not and examined whether there were significant differences in maternal outcomes and neonatal outcomes. Bivariable and multivariable analyses were performed. RESULTS Of 41,943 eligible deliveries included in the analysis, 4,705 (11.2%) patients had a penicillin allergy history documented in their electronic medical record and 37,238 (88.8%) did not. Even after adjusting for potential confounders, patients with a documented penicillin allergy had a higher risk of postpartum endometritis (aOR 1.46 (95% CI 1.01-2.11) and a higher risk of their neonates having a postnatal hospital stay lasting more than 72 hours (aOR 1.10 (95% CI 1.02-1.18). There were no significant differences seen in the other maternal and neonatal outcomes in both bivariable and multivariable analyses. CONCLUSION Pregnant patients who are labelled as having a penicillin allergy are more likely to have postpartum endometritis, and neonates born to mothers who are labelled as having a penicillin allergy are more likely to have a postnatal hospital stay lasting >72 hours. Pregnant individuals with a documented penicillin allergy were significantly more likely to receive alternative non-beta-lactam antibiotics, and may have benefitted from having more details of their allergy history available as well as allergy testing.