Classification of the nonstress test and fetal outcome in 1,056 pregnancies.

Abstract

During a 2 1/2-year period, 1 056 pregnant women (1 072 fetuses) were monitored with the nonstress test (NST) in the antenatal period. Testing time was 30 minutes. The NST was classified into one of four classes: normal, suspect pathological, slight pathological, and severe pathological. In 88.5% of the pregnancies, all NSTs were normal. Suspect, slight, or severe pathological NSTs occurred at least once in 8.1%, 2.1%, and 1.3% of the women respectively. All women with a severe pathological NST had high-risk complications. Lethal malformations excluded, there were only two perinatal deaths among the tested women. In the four different classes, the frequencies of cesarean section were 11%, 17%, 41%, and 79%. One-minute Apgar scores were less than 7 in 5%, 12%, 41%, and 64%. The need for referral to neonatal intensive care was 19%, 40%, 41%, and 93% respectively. A normal NST predicted normal fetal outcome in an excellent way, while the three pathological classes appeared to represent different degrees of impending fetal jeopardy.