Impact of labor before delivery on necrotizing enterocolitis in very low birth weight infants

BackgroundNecrotizing Enterocolitis (NEC) is multifactorial, and the gut microbiome may contribute. Neonatal gut colonization differs by delivery mode; while delivery mode has not been linked to NEC in prior studies, the impact of labor prior to delivery is unknown. Our objective was to investigate the impact of labor prior to delivery on NEC incidence in very low birth weight (VLBW, <1500 g) infants.MethodsWe performed a single-center retrospective cohort study of VLBW infants 23 0/7-34 6/7 weeks gestation born at our center between 03/25/2012 and 12/31/2023. Infants with congenital anomalies or who died prior to admission were excluded. Labor was defined as uterine contractions with cervical dilation or effacement. When cervical exam was undocumented, labor was determined by presence of regular contractions >1 h before delivery. Multivariable logistic regression evaluated the association between labor before delivery and NEC after adjusting for baseline differences.ResultsAmong 1,951 infants, 1,175 (60.2%) were exposed to labor before delivery. Groups differed by gestational age, birth weight, chorioamnionitis, maternal diabetes, multiple gestation, and small for gestational age. Exposure to labor had lower odds of NEC (odds ratio [OR] = 0.606, 95% confidence interval [CI]: 0.407-0.902, p = 0.01), compared to those unexposed. This association remained significant after adjustment (adjusted OR = 0.614, 95% CI: 0.384-0.983, p = 0.04). There was no difference in surgical NEC.ConclusionsLabor prior to delivery was associated with lower odds of NEC in this VLBW cohort, highlighting the potential importance of perinatal microbial exposures and suggesting new avenues for NEC risk stratification and prevention.