Effect of exercise on Maternal Hemodynamics and Placental Blood Flow in Healthy Women

Abstract

Intervillous placental blood flow responses to standardized exercise during late pregnancy were studied using a Xenon technique in 25 healthy women. Thirteen of them were studied twice between the 32nd and 38th weeks of pregnancy, with mean 32 (range 22 to 40) days between the studies. At the end of a 6-min exercise, mean maternal heart rate had risen from 77 +/- 10 (SD) to 154 +/- 11 beats/min, amounting to 63% of maximal oxygen uptake. Stroke volume rose by 9%, cardiac output by 65% and cardiac index by 71% as a consequence of exercise, but peripheral vascular resistance declined by 41%. The placental blood flow was at a similar level after the exercise as before the exercise, being 95 +/- 19 (mean +/- SD) ml/min/100 ml of intervillous space before, 98 +/- 24 one min after, and 93 +/- 16 30 min after the cessation of exercise. No change was found in the level of placental blood flow between the 32-34th and 37-38th weeks of pregnancy. The placental blood flow had a positive correlation with maternal weight, mean arterial blood pressure and with diastolic blood pressure. Maternal heart rate, cardiac output, cardiac index, placental weight and the birth weight of the infant was not correlated with placental blood flow. It is concluded that in normal pregnancy a short submaximal exercise has little effect on placental blood flow measured after exercise.

Effect of maternal exercises on biophysical fetal and maternal parameters: a transversal study

“…Similar studies have concluded that, during normal pregnancy, a short submaximal exercise session has little effect on placental blood flow after exercise, (23,27,28) as it was found in this study, in which the uterine arteries showed no difference, and the umbilical artery revealed vasodilation with no clinical consequences, probably due to a fetal mechanism to ensure homeostasis. (24) …”

Fetal wellbeing may be compromised during strenuous exercise among pregnant elite athletes

“…Rauramo and Forss14 found unchanged uterine blood flow following exercise. However, the study used Xenon clearance techniques, and that methodology was probably not reflecting uterine artery volume flow.…”

“…One experimental study in pregnant sheep found reduced volume blood flow by 15–20% in response to different exercise regimens 13. Studies in pregnant women have produced contradictory results 14–16. There are several Doppler ultrasound studies on exercise-related changes in umbilical and uterine artery waveforms,17–20 but we have found no studies on uterine artery volume blood flow during strenuous exercise in pregnancy.…”

A Prospective Study of the Association Between Vigorous Physical Activity During Pregnancy and Length of Gestation and Birthweight

“…Animal studies suggest decreased uterine blood flow during physical activity (5-8), but studies in women are inconclusive (9-11). Several studies have reported an increase in fetal heart rate during maternal physical activity (12-16), although changes in fetal heart rate may occur in response to maternal epinephrine and may not reflect a decrease in oxygen (12-15).…”