A prospective multi-institutional study of antepartum fetal heart rate monitoring. II. Contraction stress test versus nonstress test for primary surveillance.

This study includes, 1,542 patients who underwent nonstress tests (NSTs) for primary fetal surveillance and 4,626 patients who underwent contraction stress tests (CSTs) for primary fetal surveillance. All pregnancies were at increased risk for uteroplacental insufficiency. The results showed that the two groups were comparable according to maternal diagnostic criteria for testing. Those patients who underwent NSTs as primary surveillance had a 2.9% incidence of intervention because of abnormal test results while the CST group had a 4.5% incidence of intervention because of abnormal test results ( p less than 0.05). The NST group had significantly more respiratory distress syndrome, intrauterine growth retardation, birth weight less than 2,500 gm, and 5-minute Apgar scores less than 7. The antenatal death rate was nearly eight times higher in the NST group (7.8/1,000 versus 1.1/1,000 in the CST group) (p less than 0.05). After correction for congenital anomalies and unrelated causes, the NST group had an antenatal death rate of 3.2/1,000 versus 0.4/1,000 in the CST group (p less than 0.05); there was still an antenatal death ratio of 8:1.