"Does severity of isolated oligohydramnios at term matter?"

To examine the correlation between the severity of isolated oligohydramnios at term and adverse perinatal outcomes, aiming to inform clinical management strategies.

This retrospective cohort study conducted at a tertiary university-affiliated hospital from 2028 to 2024 included women at 37-42 weeks of gestation diagnosed with isolated oligohydramnios, defined as an amniotic fluid index (AFI) ≤ 5 cm. Exclusion criteria included maternal comorbidities, fetal anomalies, abnormal Doppler studies, multifetal pregnancies, and fetuses with growth restriction or small for gestational age. Participants were categorized into severe (AFI ≤ 2 cm) and mild (AFI 2.1-5.0 cm) oligohydramnios groups. The primary outcome was a composite measure of adverse perinatal outcomes, including cesarean or vacuum delivery for fetal distress, 5-min Apgar score < 7, umbilical artery pH < 7.1, meconium-stained amniotic fluid, neonatal intensive care unit admission, or birth asphyxia.

Among 29,759 deliveries during the study period, 432 (1.5%) involved isolated oligohydramnios, of which 66 (15%) had severe and 366 (85%) had mild oligohydramnios. The incidence of adverse perinatal outcomes was significantly higher in the severe group compared to the mild group (22.7% vs. 12.8%; p = .039). Severe oligohydramnios remained an independent predictor of adverse outcomes after adjusting for confounders, with an adjusted odds ratio of 1.96 (95% CI:1.09-3.779, p = .044).

Severe isolated oligohydramnios at term is associated with nearly double the risk of adverse perinatal outcomes compared to mild cases. These findings underscore the importance of close monitoring and timely delivery planning in severe cases of isolated oligohydramnios at term.