Mode of delivery and neonatal outcomes with early preterm severe preeclampsia: does fetal growth restriction matter?

OBJECTIVE: Severe preeclampsia diagnosed at or prior to 34 weeks is an indication for preterm delivery. Many patients with severe preeclampsia develop fetal growth restriction as a result of the placental dysfunction associated with both conditions. The ideal mode of delivery in cases of preterm severe preeclampsia with fetal growth restriction remains controversial, with providers often proceeding directly to cesarean delivery rather than attempting a trial of labor due to theoretic concerns about the harms of labor in the face of placental dysfunction. There are limited data supporting this approach. This study evaluates whether the presence of fetal growth restriction affects the ultimate mode of delivery or neonatal outcomes among pregnancies with severe preeclampsia undergoing induction of labor at or before 34 weeks.

METHODS: This was a retrospective cohort study of singletons with severe preeclampsia undergoing induction of labor ≤ 34 weeks at a single center between January 2015 and April 2022. The primary predictor was fetal growth restriction, defined as estimated fetal weight < 10th percentile for gestational age on ultrasound. Mode of delivery and neonatal outcomes were compared between those with and without fetal growth restriction using Fisher's exact and Kruskal-Wallis tests, and multivariate logistic regression was used to obtain adjusted odds ratios.

RESULTS: 159 patients were included ( N  = 117 without fetal growth restriction, N  = 42 with fetal growth restriction). There was no difference in vaginal delivery between the groups (70% vs 67%, p  = .70). While those with fetal growth restriction had a higher incidence of respiratory distress syndrome and longer neonatal hospital stay, these differences were not statistically significant after adjusting for gestational age at delivery. There were no significant differences in other neonatal outcomes, including Apgar score, cord blood gases, intraventricular hemorrhage, necrotizing enterocolitis, neonatal sepsis, and neonatal demise.

CONCLUSION: For pregnancies complicated by severe preeclampsia that require delivery ≤ 34 weeks, the likelihood of successful vaginal delivery following induction of labor does not differ based on presence of fetal growth restriction. Furthermore, fetal growth restriction is not an independent risk factor for adverse neonatal outcomes in this population. Induction of labor should be considered a reasonable approach and should be routinely offered to patients with concurrent preterm severe preeclampsia and fetal growth restriction.