Fetal heart rate decelerations during a nonstress test.

In a review of 2000 nonstress tests (NSTs) on 972 pregnant women at high risk at the authors' institution, 94 exhibited fetal heart rate (FHR) decelerations in response to fetal activity in 110 (46.6%) of the 236 NSTs. The NST results were interpreted as either reactive (178) or nonreactive (58). Of those cases with an FHR deceleration pattern, an abnormal cord position was observed in 55.3% (X2 = 68; P less than .001). Of the 74 patients who went into labor, 59.5% demonstrated variable FHR decelerations. Moreover, 8.5% required cesarean section for fetal distress. Of greater importance, 3 intrauterine fetal deaths occurred that appeared to be related to the abnormal cord position. FHR decelerations may occur during reactive as well as nonreactive NSTs. When FHR decelerations are present, they may signify some form of abnormal cord position and require further evaluation by ultrasonography and a contraction stress test.