Influence of maternal exercise on fetal heart response during labor and delivery

OBJECTIVES: The purpose of this study was to determine if prenatal exercise alters the maternal and fetal heart responses during labor and delivery. We hypothesized that fetuses of exercising mothers would exhibit a lower baseline heart rate (HR), increased HR variability (HRV), and no differences in fetal heart accelerations and decelerations. DESIGN: This study employed a cross‐sectional design. METHODS: The Modifiable Physical Activity Questionnaire was used for group classification. Exercising women were those participating in 30 minutes of moderate‐to‐vigorous exercise at least 3×/week throughout the entire pregnancy. Women achieving a lower dose of exercise were classified as non‐exercisers. Cardiotocography recordings during the first hour of labor and delivery assessed fetal baseline HR, HRV, accelerations, decelerations, and contractions. ANCOVA analyses were performed to assess group differences in these outcomes and were adjusted for maternal body mass index. RESULTS: Thirty‐one women were included in the analyses. No group mean differences were found for maternal and fetal characteristics, except for maternal age (EX: mean (SD) 28.5 (±4.6y) vs NON‐EX: 24.1 (±1.2y)). After controlling for body mass index, no statistical differences in maternal HR response (β = 3.9, SE = 5.0, 95%CI −6.4‐14.2) or fetal HR response (β = 3.9, SE = 2.5, 95%CI −1.2‐9.11), accelerations and decelerations (β= −0.03, SE = 0.4, 95%CI −0.9‐0.8; β= −0.10, SE = 0.4, 95%CI −0.8‐0.9, respectively), or HRV (β = 0.6, SE = 1.7, 95%CI −2.8‐4.0) were observed. CONCLUSIONS: Based on the findings of this study, we found no evidence that maternal exercise during pregnancy was associated with maternal or fetal HR response during labor and delivery. These data suggest maternal exercise may not elicit positive or negative effects on maternal and fetal cardiovascular responses to the physiological stress of labor and delivery.