Antepartum predictors of fetal distress in postterm pregnancy.

The purpose of this study was to determine the efficacy of combining nonstress testing with ultrasound assessment of amniotic fluid volume for the antenatal evaluation of the postterm fetus. Postterm patients (884) were managed with amniotic fluid assessments and nonstress tests (including evaluation for variable and late decelerations) twice a week. There were no perinatal deaths or major neonatal morbidity. However, the antenatal testing sensitivity, specificity, negative, or positive predictive values were not improved by combining the two tests. Individually, amniotic fluid assessment was just as accurate a predictor of fetal well-being and was a significantly more sensitive test than the nonstress test. In addition, antenatal predictors of fetal distress and intrapartum signs of fetal distress were almost exclusively those reflective of umbilical cord compromise. These findings stress the importance of antenatal screening for signs of umbilical cord compromise as an early indication of potential fetal compromise. Although the results also suggest that amniotic fluid assessment is superior to the nonstress test, they do not conclusively support the use of amniotic fluid assessment as the sole parameter for postterm antenatal surveillance.