Maternal exercise benefits mother and infant

By Megan Rauscher

NEW YORK (Reuters Health) - Exercise during pregnancy has cardiovascular benefits not just for the mother but for the developing fetus as well, according to research presented Monday at the 121st annual meeting of the American Physiological Society, part of the Experimental Biology 2008 scientific conference.

The results of this pilot study "imply an exciting potential benefit of maternal exercise on fetal cardiac autonomic nervous system regulation," Dr. Linda E. May from Kansas City University of Medicine and Biosciences in Kansas City, Missouri told Reuters Health.

The autonomic nervous system controls the body's involuntary activities, such as the beating of the heart, blood pressure, breathing rate, and functions in the internal organs.

May and colleagues tested the hypothesis that fetuses exposed to exercise in the womb have better autonomic function compared with that of fetuses not exposed to exercise.

The researchers measured the fetal heart rate and heart rate variability between 28 to 36 weeks of pregnancy in women who exercised and those who did not -- 5 women performed moderate intensity aerobic exercise for at least 30 minutes, 3 times per week, while the other 5 did not partake in a regular exercise regime.

In a telephone interview with Reuters Health, May said that fetuses exposed to maternal exercise had significantly lower heart rates than fetuses not exposed to exercise. At each stage of pregnancy, the differences between the average fetal heart rates of the two groups were statistically significant, she noted.

At 32 weeks of pregnancy, the fetal heart rate variability was also significantly higher in the exercise group than in the non-exercise group. This relationship was weaker but still evident at 36 weeks of pregnancy.

"When the mom exercises during pregnancy, the unborn baby gets the same type of training effect that you would see in an adult - so you see the lower heart rate and also improved heart rate variability, which is evidence of improvements in the nervous system of the heart."

"Maternal exercise may be the earliest intervention to improve the heart of children and possibly the best," May concluded.