Evidence of fetal cerebral vasodilatation induced by submaximal maternal dynamic exercise in human pregnancy

Abstract

To investigate the relationship between maternal exercise and fetal circulatory responses in humans during the third trimester of pregnancy, changes in uterine, umbilical and fetal cerebral circulations were measured by pulsed-Doppler ultrasound method in 14 healthy volunteer pregnant women before and just after a moderate non-exhaustive exercise. Maternal heart rate increased significantly reaching 80% of the theoretical maximal heart rate (TMHR) while uterine resistance indices did not change. The fetal heart rate and umbilical mean velocity were unchanged while umbilical resistance index decreased slightly (0.58 +/- 0.06 versus 0.62 +/- 0.07, P < 0.05). The fetal internal carotid artery mean velocity increased (23.2 +/- 5.3 versus 20.4 +/- 4.1 cm/s, P < 0.02) and the cerebral resistance index decreased (0.71 +/- 0.11 versus 0.80 +/- 0.10, P < 0.01). We conclude that submaximal maternal exercise at 80% of TMHR does not significantly alter uterine perfusion but involves a slight fetal cerebral vasodilation which could be due to a moderate fetal hemoglobin desaturation.

Physiology of Prenatal Exercise and Fetal Development

“…A few studies found no change in FHR during or immediately after a maternal exercise session (Marsal et al 1979;Artal et al 1995;Bonnin et al 1997). Some studies found a few cases of decreased FHR immediately after a single session of maternal exercise (Jovanovic et al 1985;Watson et al 1991;Manders et al 1997).…”

“…While power in defined frequency bands cannot be used as a proxy for cardiac output, the finding is intriguing and warrants further investigation. Further, fetal internal carotid artery mean velocity increased and fetal cerebral resistance index decreased suggesting vasodilation (Bonnin et al 1997). The evidence overwhelmingly shows that maternal exercise does not have adverse fetal cardiovascular effects (Kennelly et al 2002b).…”

Does exercise training during pregnancy influence fetal cardiovascular responses to an exercise stimulus? Insights from a randomised, controlled trial

“…They did not observe significant exercise-induced changes in umbilical perfusion,4–7 9–13 or even improvements due to decreased vascular resistance were reported 8. Two studies suggested fetal cerebral vasodilatation with maternal exercise 4 13. More discrepancies exist on the acute response of fetal HR (FHR) to late-pregnancy maternal exercise.…”

“…Several studies evaluated the effects of a single bout of dynamic, submaximal exercise (usually, cycle-ergometry at ≤80% age-predicted maximum heart rate (HR max )) on the vascular resistance of the umbilical3–13 or fetal cerebral circulation in non-athletic, healthy women during the last trimester of uncomplicated pregnancy 4 13. They did not observe significant exercise-induced changes in umbilical perfusion,4–7 9–13 or even improvements due to decreased vascular resistance were reported 8.…”

“…More discrepancies exist on the acute response of fetal HR (FHR) to late-pregnancy maternal exercise. Several studies reported significant increases in FHR6 12–14 or considerable individual variability in the FHR response,5 while others did not observe any change 4 11. A transient fetal impairment has been described at high exercise intensities (>90% HR max ), as described by FHR decrease and eventual fetal bradycardia 14…”