Neonatal Antibiotic Exposure and Neonatal Unit Admission in Infants Born to Mothers with Peripartum Bacteraemia: An Eight-Year Retrospective Cohort Study

Background: As maternal peripartum bloodstream infection can lead to early-onset neonatal sepsis, infants born to affected mothers are frequently separated from their mothers for monitoring, investigation and treatment. Our aim was to determine the risk of neonatal sepsis in infants born to mothers with microbiologically confirmed peripartum bacteraemia by examining the microbiology, maternal severity, neonatal management and outcomes of peripartum maternal bacteraemia. Methods: We conducted a single-centre, retrospective, observational study at a tertiary referral maternity hospital over eight years (2018–2025). We identified all clinically significant maternal bloodstream infections with a blood culture taken between 24 hours before and 4 hours after delivery, and reviewed maternal and neonatal characteristics, management and outcomes. Categorical variables were compared using Fisher's exact test and continuous variables using the Mann–Whitney U test, with relative risks (RR) and 95% confidence intervals (CI). Results: There were 104 episodes among 64,436 births (1.61 per 1,000). The most common isolates were Escherichia coli (21.2%), group B streptococcus (19.2%) and viridans group streptococci (17.3%); Enterobacterales were more common before 37 weeks than at term (RR 2.67, 95% CI 1.45–4.89). Maternal sepsis or septic shock occurred in 11 women (10.6%), with no maternal deaths, and was most strongly associated with E. coli (RR 6.52, 95% CI 2.10–20.29). Among 94 liveborn infants there were no neonatal deaths and no culture-confirmed early-onset sepsis. Thirty-nine had clinical symptoms, of whom five (four preterm) developed clinical early-onset sepsis; the remaining 55 remained clinically well throughout. Nonetheless, 84 infants (89.4%) received antibiotics. Of the 55 infants who remained clinically well, 46 (83.6%) received antibiotics and 29 (52.7%) were separated from their mothers on the basis of the maternal bacteraemia rather than neonatal illness. Conclusions: In this microbiologically confirmed cohort, peripartum maternal bacteraemia caused substantial maternal morbidity but no culture-confirmed early-onset neonatal sepsis, despite high neonatal antibiotic exposure. These findings identify a clear opportunity for neonatal antimicrobial stewardship and for reducing neonatal unit admission and mother-infant separation, particularly in well, term infants.