Fetal Bradycardia in Response to Maternal Hypothermia [15O

Abstract

INTRODUCTION: Fetal bradycardia, especially if it develops abruptly in the setting of a normal fetal heart (FHR) tracing, is most often associated with fetal compromise. The differential diagnosis may include numerous maternal, placental, and fetal conditions that would prompt emergent delivery. These causes are usually associated with an absence of FHR accelerations and decreased or absent variability. On the other end of the spectrum, fetal tachycardia also has numerous causes, one of which is maternal fever (or hyperthermia). Therefore, it is plausible that the opposite effect of a low maternal temperature or hypothermia might produce fetal bradycardia. The purpose of this case series is to demonstrate this finding. METHODS: 6 cases of fetal bradycardia associated with maternal hypothermia were collected. Data collection included gestational age at presentation, maternal medical condition, maternal temperature, FHR baseline, presence and/or absence of FHR variability and accelerations, and pregnancy outcome. RESULTS: All 6 cases demonstrated FHR baselines in the 80–90s in the setting of maternal hypothermia. Maternal temperatures ranged from 92.1–96.9 0F. All had moderate variability with the presence of accelerations. All FHR baselines returned to normal with correction of maternal temperature. No adverse outcomes were seen in the 6 neonates post-delivery. CONCLUSION: These cases demonstrated fetal bradycardia can be seen in the presence of maternal hypothermia. The appearance of the FHR tracing is reassuring, except for the baseline. Therefore, emergent delivery is not indicated. The FHR baseline returns to normal with correction of maternal temperature. The overall clinical picture should be taken into consideration before proceeding with delivery.