Clinical significance of fetal heart rate patterns during labor. VI. Early decelerations.

In a population of high-risk patients who had continuous "direct" monitoring during labor, 598 (46%) had no decelerations during the first stage, while 247 (19%) had presented early decelerations before completion of dilatation. The clinical characteristics, the fetal heart rate (FHR) baseline alterations, and neonatal outcome were compared between these two groups: there were no differences in any of the aspects evaluated, except that there was transient tachycardia more often among the early-decelerations group. The patients who had no decelerations were subdivided into vaginal deliveries and cesarean deliveries, and the same parameters were compared again: the cesarean section group had longer recordings and more contractions, lower Apgar 1 and 5 minute scores, and higher incidences of Apgar scores less than or equal to 6 at 1 minute, while all other aspects were similar. A possible explanation was that 82% of cesarean sections were done under general anesthesia and only 3% of vaginal deliveries. The implication of ruptured membranes in the etiology of early decelerations was extensively reviewed and discussed in view of these findings. It is concluded that amniotomy does not seem a maneuver deleterious to the fetal well-being.