Intrapartum fetal heart rate monitoring. VI. Prognostic significance of accelerations.

The fetal heart rate (FHR) tracings of 1,996 fetuses were analyzed to assess the prognostic value of accelerations in early labor and just prior to delivery. Accelerations were divided into periodic and sporadic types according to their association or lack of association with uterine contractions. It is shown that two or less sporadic accelerations per 30 minutes are unfavorable. Three accelerations indicate fetal well-being as much as any higher number of accelerations per 30 minutes. FHR abnormalities coexistent with three or more sporadic accelerations were found to have a better prognosis than FHR abnormalities associated with two or less sporadic accelerations. Fetuses exhibiting low FHR variability commonly showed lack of accelerations, whereas normal FHR variability was almost invariably accompanied by sporadic accelerations. The pathogenesis of accelerations is discussed. It is concluded that accelerations are indicators of fetal well-being, whereas the lack of accelerations with lack of reactivity to manipulation of the fetus may be indicative of severe fetal hypoxia with fetal acidemia. This conclusion is supported by fetal outcome and determination of pH from fetal scalp blood.