Maternal and Fetal Outcome in Cases of Oligohydromnios Diagnosed After 34 Weeks’ Gestation

Abstract

Background: Oligohydramnios after 34 weeks’ gestation is a common indication for heightened fetal surveillance. However, the true burden of maternal and neonatal morbidity associated with isolated third trimester oligohydramnios in low resource settings is incompletely characterised.

Methods: We conducted a hospital based prospective cohort study at MVJ Medical College & Research Hospital, Bengaluru, enrolling 200 singleton pregnancies between 34 + 0 and 41 + 6 weeks. Amniotic fluid index (AFI) was measured by the four quadrant technique at admission and women were stratified into an oligohydramnios group (AFI ≤ 5 cm; n = 100) and a normohydramnios control group (AFI > 5 – 24 cm; n = 100). Exclusion criteria were membrane rupture, major fetal anomalies, multifetal gestation and significant medical disorders. Primary fetal outcomes were intra uterine growth restriction, intrapartum distress, Apgar scores, neonatal intensive care unit (NICU) admission and early neonatal morbidity/mortality. Maternal outcomes included labour induction and operative deliveries.

Results: Women with oligohydramnios had markedly higher odds of meconium stained liquor (66 % vs 18 %; OR 8.9), caesarean delivery for non reassuring fetal status (72 % vs 32 %; OR 5.8), and low 5 minute Apgar score < 7 (56 % vs 22 %; OR 4.5) (all p < 0.001). NICU admission was required in 44 % versus 12 % (OR 5.7), while early neonatal death occurred in 4 % versus 1 % (p = 0.17). Mean birthweight was lower in the oligohydramnios group (2.66 ± 0.37 kg vs 2.84 ± 0.39 kg) but the proportion < 2.5 kg did not differ significantly.

Conclusion: An admission AFI ≤ 5 cm reliably identifies pregnancies at increased risk of intrapartum compromise and early neonatal morbidity. Incorporating point of care AFI into the labour ward “admission test” may facilitate timely operative intervention and improve perinatal outcomes without a commensurate rise in mortality.