Decreased amniotic fluid index in low-risk pregnancy.

Objective: To evaluate the perinatal outcomes of pregnancies complicated by isolated decreased amniotic fluid volume (AFI) after 30 weeks' gestation (AFI < or = 5 or > 5 cm but < 2.5th percentile).

Study Design: We retrospectively studied 150 low-risk singleton pregnancies > 30 weeks' gestation with decreased AFI. We also compared the outcomes of 57 pregnancies with AFI < or = 5 cm to those of 93 pregnancies with AFI > 5 cm but < 2.5th percentile (borderline AFI). Pregnancy outcome was assessed with respect to antepartum, intrapartum and neonatal measures. Statistical significance (P < .05) between groups was determined by means of the Student t test and chi 2 analysis.

Results: There were no statistically significant differences between pregnancies with AFI < or = 5 cm and those with AFI > 5 cm but < 2.5th percentile with respect to labor induction for an abnormal nonstress test (7.0% vs. 7.5%, overall 7.3%), cesarean sections for fetal heart rate abnormalities (7.0% vs. 7.5%, overall 7.3%), presence of meconium (16.1% vs. 15.7%, overall 16%) and Apgar score < 7 at five minutes (0 vs. 1.1%, overall 0.66%). There were no perinatal deaths in either group. Antepartum variable decelerations were more common in pregnancies with AFI < or = 5 cm as compared to those with AFI > 5 cm but < 2.5th percentile (63.1% vs. 45.1%, P = .007; overall 53.3%).

Conclusion: With antepartum monitoring, perinatal outcome in low-risk pregnancies with an isolated decreased AFI after 30 weeks' gestation (< or = 5 or > 5 cm but < 2.5th percentile) appears to be good.