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 (ß = 3.9, SE = 5.0, 95%CI -6.4-14.2) or fetal HR response (ß = 3.9, SE = 2.5, 95%CI -1.2-9.11), accelerations and decelerations (ß= -0.03, SE = 0.4, 95%CI -0.9-0.8; ß= -0.10, SE = 0.4, 95%CI -0.8-0.9, respectively), or HRV (ß = 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.

Activity in Pregnancy for Patients with a History of Preterm Birth.

Preterm birth remains a leading cause of neonatal morbidity and mortality throughout the world. Numerous risk factors for preterm birth have been identified, including non-Hispanic black race, a variety of social and behavioral factors, infections, and history of a prior preterm delivery. Of these, a history of prior spontaneous preterm birth is one of the strongest risk factors. Traditionally, women with a history of preterm birth or those deemed at high risk for preterm delivery have been placed on bed rest or a reduced activity regimen during their pregnancy. However, there is little evidence to support this recommendation. Recent research has suggested that regular physical activity and exercise during pregnancy is safe and does not increase the risk of preterm delivery. Therefore, physicians should encourage women with a history of preterm birth to exercise throughout pregnancy according to guidelines published by the American College of Obstetricians and Gynecologists as long as they are receiving regular prenatal care and their current health status permits exercise. However, there are no randomized controlled trials evaluating exercise prescription in women with a history of preterm birth, hence additional research is needed in this area.