IS FETAL HEART-RATE-VARIABILITY A GOOD PREDICTOR OF FETAL-OUTCOME

Objective. The purpose of this study was to investigate, in a prospect ive manner, whether fetal heart rate (FHR) variability serves as a rel iable single predictor of fetal outcome. Methods. We undertook a prosp ective study of 2,200 consecutive deliveries. Preterms <37 weeks, twin s, stillbirths and fetal malformations were excluded from the study. F HR tracings were analyzed for variability in every delivery. Three win dows were evaluated: 1) early in labor (30 min); 2) in the active phas e of labor - 1 h prior to complete cervical dilatation (30 min); and 3 ) throughout the second stage of delivery, in segments of 30 min. Usin g the tracings taken at admission and prior to delivery, FHR variabili ty was scored according to five previously used evaluative methods, an d was correlated to the following three fetal outcome parameters: a) a rterial cord blood pH <7.2, >7.2; b) 5-min Apgar >6, >7; and c) immedi ate outcome ('good' defined as newborn going home after 2-5 days, with no neonatal intensive care unit (NICU) admission). Results. 1. The ma jority of cases with adverse fetal outcome exhibited good FHR variabil ity (mean, 80%). 2. Low FHR variability is not common in newborns with adverse general outcome (mean, 11.5%).3. The predictability of FHR va riability (using the five most common scoring methods) for evaluating adverse fetal outcome revealed low sensitivity (mean, 20.3%) and low p redictive value (mean, 11.6%). Conclusion. FHR variability by itself c annot serve as the only indicator of fetal wellbeing. The presence of low variability should alert the physician; however, good FHR variabil ity should not be interpreted as reassuring.