Clinical implications of prospective antepartum fetal heart rate testing

Nonstressed fetal heart rate testing was evaluated in the prospective management of 441 high-risk pregnancies in which delivery was effected between July 1, 1977 and May 1, 1979. In group I, 297 patients underwent 668 nonstress tests (NSTs); all had subsequent contraction stress tests (CSTs) which formed the basis of their management. In group II, 144 women had 293 NSTs; CSTs (99) were performed only when preceding NSTs were nonreactive; antenatal management evolved from the outcome of either nonstress testing or contraction stress testing when applicable. Perinatal outcome was correlated only with tests performed within 1 week of delivery. Both groups had equal frequencies of reactive NSTs; good fetal outcome was usually predicted by normal NST reactivity. Omission of CSTs when preceding NSTs were reactive did not alter perinatal outcome. NST nonreactivity is less specific, although generally associated with a higher incidence of perinatal morbidity and intrauterine growth retardation (UGR). CSTs more effectively separate the nonreactive fetuses with low risk of compromise (CST = negative) from those most compromised (CST = equivocal or positive).