THE VALUE OF A NEGATIVE ANTEPARTUM TEST - CONTRACTION STRESS TEST ANDMODIFIED BIOPHYSICAL PROFILE

Objective: To examine the outcome of pregnancies in highrisk patients whose last antepartum fetal assessment was a negative contraction stre ss test (CST) or a negative modified biophysical profile. Methods: Twe nty-nine hundred ninety-four women who received modified biophysical p rofiles were compared with 2450 who had CSTs during the preceding 3 ye ars. Pregnancy outcomes were evaluated in patients whose last test was negative. Results: Seventeen hundred fifty-three patients had negativ e modified biophysical profiles as the last test before delivery, and 1337 had negative CSTs as the last test before delivery. Adverse perin atal outcomes included perinatal death or death before nursery dischar ge, cesarean delivery for fetal distress within the first 2 hours of l abor, 5-minute Apgar score less than 7, neonatal seizures, or grade II I or grade IV central nervous system hemorrhage. Adverse outcomes occu rred in 90 patients (5.1%) whose last test before delivery was a negat ive modified biophysical profile and in 93 patients (7.0%) whose last test was a negative CST (P = .04, odds ratio 1.38, 95% confidence inte rval 1.01-1.88). Overall, there were 11 perinatal deaths, nine of whic h resulted from lethal congenital abnormalities. Conclusions: In this population, the frequency of adverse perinatal outcome following a neg ative modified biophysical profile was no greater than that following a negative CST. Further, the incidence of potentially preventable peri natal death following a negative modified biophysical profile or CST w as less than one per 1000 tested high-risk pregnancies.