Fetal heart rate tracings associated with eclamptic seizures

Background

Although there is a well-known association between fetal bradycardia and maternal eclampsia, the characteristics of fetal heart rate tracings after an eclamptic seizure have not previously been thoroughly described. Fetal heart rate changes are thought to be related to maternal lactic acidemia caused by vasospasm and uterine hyperactivity leading to placental hypoperfusion and fetal hypoxia. The decision to intervene in the case of an abnormal fetal heart rate tracing after an eclamptic seizure is often difficult; however, maternal resuscitation should be the primary focus.

Objective

This study aimed to quantify and characterize fetal heart rate changes associated with a maternal eclamptic seizure. Moreover, we sought to document subsequent obstetrical management following these seizures complicated by fetal heart rate decelerations.

Study Design

This was a retrospective study of fetal heart rate tracings associated with eclampsia during a 13-year period at a single institution. Eclampsia was diagnosed following the 2013 Executive Summary of the American College of Obstetricians and Gynecologists criteria. Tracings were independently reviewed and classified by 3 physicians using the National Institute of Child Health and Human Development Criteria. Hospital records were reviewed to ascertain obstetrical management after the eclamptic seizure.

Results

A total of 107 women were diagnosed with eclampsia from January 2009 to December 2021. Of these women, 31 experienced 34 intrapartum seizures during which time electronic fetal heart rate monitoring was ongoing. During the 34 seizures, fetal heart rate decelerations were documented in 79% of cases. The mean duration of bradycardia was 5.80±2.98 minutes with a range of 2 to 15 minutes. Fetal heart decelerations occurred, on average, 2.7±1.6 minutes after the onset of the eclamptic seizure. In half of the fetuses with fetal heart rate changes, fetal tachycardia followed, and in 48% of cases, there was minimal variability noted. As a result of the fetal heart rate tracings and clinical findings, 4 women underwent an emergent cesarean delivery, including 2 that were diagnosed with placental abruption. In this cohort, there were 4 cases of abruption. The mean duration from the seizure to delivery was 299±353 minutes. The mean neonatal cord pH was 7.20±0.11 with a mean base excess of −8.6±4.4 mmol/L. There was no perinatal death.

Conclusion

After an eclamptic seizure, 79% of fetuses demonstrated prolonged decelerations, and half of the fetuses developed fetal tachycardia after recovery from the episode of bradycardia. Despite these periods of fetal heart rate decelerations associated with eclampsia, prioritization of maternal support and stabilization resulted in a favorable perinatal outcome without immediate operative intervention in more than two-thirds of cases.