Labor Management and Neonatal Outcomes in Term Isolated Oligohydramnios Defined by the Single Deepest Vertical Pocket: A Retrospective Cohort Study.

Background/

Objectives

The clinical significance of isolated oligohydramnios at term may depend on the measurement method used. We assessed whether isolated oligohydramnios at term, defined by a single deepest vertical pocket (SDVP) below 2 cm, is associated with labor management, primary cesarean delivery, and short-term neonatal outcomes.

Methods

This retrospective cohort study included 328 singleton pregnancies delivered at 37 + 0 to 41 + 6 weeks at a tertiary center between January 2023 and May 2026. All 128 exposed pregnancies met SDVP < 2 cm; 72 AFI-only cases with SDVP ≥ 2 cm were excluded from the primary analysis. The control group comprised 200 low-risk term pregnancies with SDVP ≥ 2 cm. Primary cesarean outcomes were evaluated among women without a previous cesarean delivery. Multivariable logistic regression estimated adjusted odds ratios (aORs) with 95% confidence intervals (CIs).

Results

Labor induction was more frequent with SDVP-defined isolated oligohydramnios than with normal fluid (75.0% vs. 29.0%; p < 0.001). Among induced women, admission Bishop score, labor duration, and failed-induction rate were similar (6.3% vs. 5.2%; p = 1.000). Overall cesarean delivery, including repeat procedures, occurred in 30.5% versus 19.0% (p = 0.017). Primary cesarean delivery occurred in 25.8% and 18.5% (aOR, 1.67; 95% CI, 0.94-2.99), whereas primary cesarean delivery for fetal distress was more frequent (14.2% vs. 5.6%; aOR, 2.50; 95% CI, 1.05-5.94). Composite neonatal morbidity did not differ significantly (12.5% vs. 9.0%; aOR, 1.31; 95% CI, 0.61-2.78), nor did neonatal intensive care unit admission, cord pH, or neonatal death.

Conclusions

At term, SDVP-defined isolated oligohydramnios was associated with more labor induction, a higher crude overall cesarean rate, and more primary cesarean delivery for fetal distress. No statistically significant adjusted association was detected for primary cesarean delivery or composite neonatal morbidity; the confidence intervals do not establish equivalence or exclude clinically important differences.