A total of 4517 successful antepartum nonstress tests (NST) was performed on 2003 high- (28%) and low- (72%) risk obstetric patients. Most patients were monitored from 32 to 34 weeks' gestation onward. A reactive NST was defined as 2 accelerations in 10 minutes—15 beats/min minimum amplitude; 15 seconds minimum duration. The test was repeated at the next visit in low-risk patients with reactive NST or in 1 week in high-risk patients with this response. Nonreactive tests were followed immediately by a stress test in high-risk patients, but only after repeat nonreactive NST within 24 hours in low-risk patients. About 88% of low-risk and 86% of high-risk patients demonstrated reactive NST only. Late decelerations during subsequent stress testing or labor, low Apgar scores, and perinatal deaths were more common in low-risk pregnancies than in highrisk pregnancies and more common in those with nonreactive NST than in those with reactive NST. High-risk/reactive NST babies, however, fared better than low-risk/nonreactive NST babies. Of the 16 perinatal deaths 6 died antepartum, 2 died in labor, and 8 died as neonates. Presumed asphyxia accounted for 6 deaths while significant anomaly accounted for 5; sepsis and trauma accounted for 2 each. In only 2 instances was a reactive NST followed by a death from apparent asphyxia. Routine NST testing appears to improve the resolution of maternal risk classification and may contribute to better perinatal outcome.
From the Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, Los Angeles, California.
© 1979 The American College of Obstetricians and Gynecologists