Antepartum fetal heart rate testing: VII. The significance of fetal bradycardia

Abstract

Antepartum fetal heart rate testing (AFHRT) was utilized in the assessment of fetal status on a large clinical service. The nonstress test (NST) was used as the primary approach. The contraction stress test (CST) was used in the face of persistent nonreactivity. The significance of fetal bradycardia occurring during AFHRT was assessed. Bradycardia was defined as a fetal heart rate (FHR) of 90 bpm or a reduction in FHR of 40 bpm below baseline, for 60 seconds or greater. In a 2-year period, there were 28 cases of bradycardia during 3,754 tests. A total of 24 cases were sent for delivery on the same day while four cases were managed in variable fashion. In 16 cases the tests were classified as nonreactive (abnormal) and the patients were sent for delifery on the same day. There was a 50% incidence of emergency delivery for fetal distress in labor in this group. In eight cases the tests were classified as reactive (normal) and the patients were sent for delivery on the same day. The incidence of fetal distress in labor with emergency delivery was 50%. Five of 10 patients with decreased amniotic fluid volume either on ultrasonic evaluation or by clinical estimation developed fetal distress in labor. There were three cases of congenital anomalies and one case of intrauterine growth retardation which exhibited diminished amniotic fluid. The occurrence of fetal bradycardia during AFHRT denotes a fetus at increased risk of developing fetal distress in labor. This type of test should be considered abnormal and consideration should be given to delivery of the fetus.