Baseline characteristics of participants.

Hypertensive disorders of pregnancy (HDP) may affect fetal development and result in preterm delivery. Necrotizing enterocolitis (NEC) is a severe gastrointestinal emergency in very preterm infants (VPIs, gestational age less than 32 weeks). The relationship between maternal HDP and NEC is controversial. Objective To investigate the association between maternal HDP and NEC in VPIs.This was a multicenter retrospective cohort study based on the data from the Chinese Neonatal Network (CHNN) which were collected between January 1, 2019 and December 31, 2021. Preterm infants born between 24+0 and 31+6 weeks of gestation were divided into HDP and no-HDP groups according to the 2015 Chinese guidelines for HDP. The primary outcome was the incidence of Bell’s stage II or higher NEC. Secondary outcomes included mortality and spontaneous intestinal perforation (SIP). Of 27,660 women were included in the study analysis, 5405 (19.5%) were HDP and 22256 (80.5%) were no-HDP. NEC occurred in 5.2% (283/5,404) among HDP mothers and 5.3% (1,191/22,256) among no-HDP mothers. No significant association was observed between HDP and Bell’s stage II or higher NEC (aOR 0.87, 95% CI [0.72, 1.05]). However, even after adjustment, maternal HDP appeared to be protective for NEC requiring surgical intervention (aOR 0.60, 95% CI [0.43, 0.83]). There was no significant correlation between maternal HDP and neonatal mortality and SIP. Maternal HDP was not significantly associated with the incidence of Bell’s stage II or higher NEC. However, it was associated with the lower rate of NEC requiring surgical intervention.