Maternal and Fetal Outcomes in Idiopathic Oligohydramnios vs. Normal Amniotic Fluid Index After 34 Weeks: A Case-Control Study in Eastern India.

BACKGROUND

Oligohydramnios, traditionally associated with adverse perinatal outcomes, often prompt early delivery via caesarean section, even in otherwise uncomplicated pregnancies. However, emerging research suggests that isolated oligohydramnios may not significantly impact neonatal outcomes, warranting re-evaluation of current management strategies. This study aimed to assess maternal and fetal outcomes in patients with idiopathic oligohydramnios diagnosed between 34-40 weeks of gestation, compared to low-risk pregnancies with normal amniotic fluid volume.

METHODOLOGY: A prospective case-control study was conducted in a tertiary care hospital in Eastern India over a period of one year. The study enrolled 100 pregnant women divided into cases: women with idiopathic oligohydramnios (amniotic fluid index [AFI] ≤5 without any identifiable maternal, fetal, or placental cause) and controls: gestational age-matched women with normal AFI (5-25 cm). Maternal characteristics, labor course, mode of delivery, and neonatal outcomes were analyzed. Statistical analysis was performed using SPSS, with p<0.05 considered significant.

RESULTS

The rate of labor induction was significantly higher in cases compared to controls (50% vs. 20%, p=0.001). Meconium-stained liquor (44%) and non-reactive cardiotocography (NRCTG) (60%) were more common in the oligohydramnios group. Caesarean section rates were markedly higher among cases (78% vs. 32%, p<0.001), primarily due to fetal distress (71.8%). Newborns of cases had a higher incidence of small-for-gestational-age (SGA) status (56%). APGAR scores <7 at 1 and 5 minutes were more frequent in cases, with significantly higher neonatal intensive care unit (NICU) admissions (60% vs. 16%, p<0.001).

CONCLUSION

Isolated oligohydramnios is associated with increased obstetric interventions, higher caesarean rates, and adverse neonatal outcomes, including SGA and higher NICU admissions, despite reassuring antenatal fetal surveillance. These findings suggest the need for individualized care and close fetal monitoring rather than automatic early delivery in isolated oligohydramnios cases.