Induction of labor and perinatal outcome: the impact of the amniotic fluid index.

OBJECTIVE: The purpose was to determine the impact of the amniotic fluid index on the perinatal outcome of patients admitted for induction of labor at term.

STUDY DESIGN: Patients (n=180) included in the study were those admitted for induction of labor at 37-42 weeks' gestation, with unfavorable cervix and intact membranes. The amniotic fluid index (AFI) was determined in all patients using the four-quadrant technique within 24 h of the induction of labor. Patients were divided into two groups based on their AFI: the oligohydramnios group with AFI < or = 5 cm (n = 66) and a normal group with AFI > 5 cm (n = 114). The perinatal outcomes of the two groups were compared.

RESULTS: The two groups were similar with regard to maternal age, gestational age, and birth weight. Meconium staining of the amniotic fluid was significantly higher in the group with AFI < or = 5 cm (p = 0.040). The number of cesarean deliveries due to fetal distress was significantly higher even after adjusting for other confounding factors in the group with AFI < or = 5 cm (adjusted OR 6.52 [95% CI 1.82, 23.2]; p < or = 0.0001). There was no significant difference between the two groups with regard to Apgar scores or neonatal admission.

CONCLUSION: Induction of labor at term in patients with oligohydramnios is associated with an increased risk of cesarean delivery due to fetal distress.