Low amniotic fluid index as a predictor of adverse perinatal outcome

Objective: To determine whether an antepartum amniotic fluid index (AFI) of 5.0 cm or less is a predictor of adverse perinatal outcome. Study design: The antepartum testing records of 779 women seen over a 12-month period were reviewed. Data, including the reasons for testing, the testing results, and pregnancy outcome were abstracted from these records. Inclusion criteria included a nonanomalous fetus and delivery within 7 days of the last antepartum surveillance test (modified biophysical profile). Chi-square analysis, Fisher's exact test, t tests and receiver-operator curves (ROCs) were used for analysis. Results: An AFI of 5.0 cm or less was significantly associated with an abnormal antepartum fetal heart rate (FHR) tracing but not with cesarean delivery, meconium-stained fluid, Apgars less than 7, or NICU admission. Subjects with an AFI of 5.0 cm or less had a higher rate of cesarean for fetal distress, but this did not reach statistical significance. ROCs produced no diagnostic cutoff values for AFI or largest pocket and prediction of any of the chosen parameters. Conclusions: Antepartum oligohydramnios is associated with an increased risk of fetal heart rate abnormalities. Although in our population it is not predictive of adverse perinatal outcome as measured by low Apgars and NICU admissions, this may be reflective of the aggressive antepartum and intrapartum management that these patients received.