Delivery Mode among Patients with Oligohydramnios with or without Fetal Growth Restriction by Induction Method

Objective To evaluate the association of induction method on delivery mode in pregnancies complicated by oligohydramnios with and without fetal growth restriction (FGR).Study Design This was a secondary analysis of a National Institutes of Health funded retrospective cohort study of singleton deliveries at a tertiary-care hospital between 2002 and 2013 with diabetes, mild hypertension, and/or FGR. Chart abstraction was performed by trained research nurses. Patients with a diagnosis of fetal oligohydramnios with and without FGR were identified. Our analytic cohort was further stratified into three groups per initial induction agent: prostaglandins (PGEs) alone, PGE plus mechanical ripening, or oxytocin only. Primary outcome was mode of delivery. Secondary outcomes included indications for cesarean delivery and neonatal morbidity.Results Out of 4,929 patients in the original database, 546 subjects with fetal oligohydramnios were identified; of these, 270 were induced and included for analysis. Outcomes were compared between 171 patients who had fetuses with isolated oligohydramnios and 99 patients who had fetuses with oligohydramnios and FGR. There were no significant differences in demographic characteristics between the groups. Patients with fetuses with isolated oligohydramnios had similar rates of spontaneous vaginal delivery (SVD) when PGEs were used ( n = 44/79, 55.7% PGE alone, n = 44/76, 57.9% PGE with mechanical ripening) and when they were not used ( n = 5/13, 38.5% oxytocin alone; p = 0.43). Similarly, the majority of patients in both cohorts underwent SVD regardless of induction method ( n = 30/44, 68.2% PGE alone, n = 30/44, 68.2% PGE with mechanical ripening, and n = 6/10, 60% oxytocin alone; p = 0.90). There was no significant difference in composite neonatal morbidity.Conclusion In patients with fetuses with oligohydramnios with and without FGR, most patients delivered by SVD regardless of induction method. In this population, PGE use was associated with a high chance of SVD in patients with fetuses with suspected placental insufficiency regardless of the presence of absence of FGR.