Objective: We investigated the hypothesis that repetitive variable heart rate decelerations in labor are associated with an increased incidence of neonatal complications in premature infants.
Methods: This was a retrospective case-control study. Singleton fetuses weighing between 750 and 2500 g at 25-35 weeks' gestation were considered for the study. Fetuses delivered by Cesarean section prior to labor were excluded. Heart rate traces were retrieved from an electronic archive and were assessed for the presence of variable decelerations. Cases had at least three variable decelerations in the hour prior to delivery and were matched 1:1 with controls for gestation, sex and birth weight.
Results: A review of 6500 deliveries yielded 41 matched pairs. The groups were compared for the following outcomes. Measures of acute morbidity were cord pH at delivery, 5-min Apgar score and resuscitation; measures of chronic morbidity were intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis and death. There was no difference in measures of acute morbidity between the groups. The incidence of chronic morbid outcome measures in the cases was six (15%) vs. one (2.5%) in controls (p = 0.01).
Conclusions: This study suggests that variable decelerations in preterm infants are associated with chronic morbidity, particularly intraventricular hemorrhage through a mechanism independent of fetal acidemia. Further study is required to determine whether these infants would benefit from early Cesarean section.