664 - Impact of labor before delivery on incidence of necrotizing enterocolitis in very low birthweight infants

Publication Number: 1641.664

Neha Dhawan, Baylor College of Medicine, Houston, TX, United States; Sara Yasrebi, Baylor College of Medicine, Houston, TX, United States; Joseph Hagan, Baylor College of Medicine, Houston, TX, United States; Maya Brasher, Baylor College of Medicine, Houston, TX, United States; Monika S.. Patil, Baylor College of Medicine, Houston, TX, United States

Background: Necrotizing enterocolitis (NEC) has a mortality of 15-30% among premature infants. The etiology is multifactorial, and the gut microbiome may contribute. Prior studies show microbial colonization differs between neonates born by cesarean and vaginal deliveries, and emerging data suggests that labor before cesarean delivery may affect this further via exposure to vaginal flora. While delivery mode has not been linked to NEC in prior studies, the impact of labor prior to delivery on NEC risk has not been explored.

Objective: We aimed to investigate the impact of labor prior to delivery on NEC incidence and need for surgical intervention in very low birth weight (VLBW, < 1500g) infants.

Design/Methods: This single center retrospective cohort study used data from the Vermont Oxford Network database and medical records on VLBW infants born from 23 0/7- to 34 6/7-weeks' gestation between 01/01/2012 and 12/31/2023 at our center. Out-born infants, congenital anomalies, and those that died prior to admission were excluded. Labor was defined as the presence of uterine contractions resulting in cervical dilation or effacement. In cases where no cervical exam was documented, regular contractions for at least one hour immediately before delivery was used. Multivariable binary logistic regression was used to investigate the association of labor before delivery with NEC after controlling for baseline characteristics that differed significantly between infants exposed versus not exposed to labor before delivery.

Results: Of 1951 infants included, 1175 (60.2%) were exposed to labor before delivery. Table 1 shows maternal and infant variables for each group. Groups differed significantly by gestational age, birthweight, chorioamnionitis, maternal diabetes, multiple gestation, and small for gestational age. Infants exposed to labor had lower odds of NEC (odds ratio [OR] = 0.606, 95% confidence interval [CI]): 0.407 - 0.902, p = 0.013), compared to those not exposed to labor. This association remained significant after controlling for confounders (adjusted OR = 0.614, 95% CI: 0.384 - 0.983, p = 0.042) (Figure 1). There was no difference between groups in the need for surgical intervention for NEC.

Conclusion(s): Exposure to labor prior to delivery is associated with lower odds of NEC in this VLBW cohort. This is the first study reporting this association, highlighting the potential importance of perinatal microbial exposures and suggesting new avenues for NEC risk stratification and prevention. Further translational research may elucidate the impact of labor on the microbiome and its direct linkage to NEC incidence.

Maternal and Infant Variables by Labor Status


Association of Labor before Delivery with NEC and Surgical NEC Incidence
Figure 1. Impact of Labor vs. No Labor Before Delivery on NEC and Surgical NEC Incidence