(102) Do maternal blood pressure changes related to labor epidural affect fetal heart rate?

Cohort study of all laboring women who underwent epidural anesthesia during labor for the period October 1, 2020-December 31, 2020. Excluded were cases of elective CD, non-cephalic presentation, twins or multiples, fetal death, and gestational age < 37.0 weeks. The last maternal BP prior to initiation of epidural anesthesia and the nadir BP in the 60 minutes after epidural were recorded, together with FHR category and presence of severe (prolonged or recurrent late) decelerations in the 60 minutes before and after epidural. In the presence of severe decelerations, the seconds FHR spent below baseline were calculated. Binary logistic regression analysis was used to control for confounders (SPSS 28).

Results: A total of 438 women fulfilled the study criteria. Severe maternal hypotension ((i.e. decrease of systolic BP to < 100 mm Hg or >20% decrease below pre-epidural) occurred in 158 cases (36%) and was significantly correlated with occurrence of severe FHR decelerations (P=0.031), seconds below baseline after epidural (P=0.015), but not worsening in FHR category (P=0.32). In the entire cohort there was a correlation between duration of FHR below baseline after epidural and difference in systolic BP (P=0.008) or % change in systolic BP pre- to post-epidural (P=0.006). In the absence of severe maternal hypotension, % change in systolic BP was not significantly associated with occurrence of severe FHR decelerations (P=0.09), changes in FHR category (P=0.84), or seconds below baseline after epidural (p=0.198).

Conclusion: Severe but not mild maternal hypotension can lead to severe FHR decelerations.