Exercising in pregnancy good for child

You feel that life inside you, both physically independent and braided with your own. Now, new research suggests that the bond may be stronger than had been suspected.

When you exercise during pregnancy, your baby is not, as most of us would have thought, a passive, floating passenger (and ballast on the bladder).

Instead, he or she may be actively joining in the workout, with the fetal cardiac system growing stronger and healthier as a result of the workouts.

This training response lingers apparently even after birth, the new science shows. Babies born to mothers who exercised while pregnant were found to have healthier hearts than other infants a full month after delivery.

For the study, which was presented this week at the Experimental Biology 2011 meeting in Washington, researchers from the Kansas City University of Medicine and Biosciences revisited a group of 61 healthy women, ages 20 to 35, who’d been part of a pilot study of exercise, pregnancy and foetal heart health.

About half of the women had exercised regularly during their pregnancies, jogging, power-walking or otherwise working out at a moderate pace at least three times a week. Some also had lifted light weights or practised yoga. But their primary activity had been aerobic.

The other half of the mothers-to-be “were normally active but did not engage in formal exercise,” said Linda E May, an exercise physiologist who led the study. To gather the necessary data, Dr May originally asked the women to report to a lab three times during the latter stages of their pregnancies—at weeks 28, 32 and 36—for a non-invasive examination of their babies’ cardiac health.

What she hoped to discover was just how much a mother’s workout would affect her unborn child’s heart. Years ago, scientists showed that a fetus’s heart rate increases while its mother is exercising. But many early researchers had considered this response transient, lasting only while the mother worked out.

Dr May, however, wondered whether an unborn child’s heart might be more permanently remodelled by a mother’s workouts. In most people, exercise leads over time to a slower heart rate and greater heart-rate variability, or beat-to-beat variations between heartbeats. Both measures are generally accepted as indicative of heart health. This is known as the exercise training response and is considered evidence that a person’s heart has grown stronger and more efficient.

Unborn children, as it turned out, did exhibit a training response, even though their mothers were seemingly doing all of the work. When Dr May examined the fetal cardiac readings, in an earlier report published last year, she found that fetuses whose mothers had exercised showed lower heart rates and greater heart-rate variability than those whose mothers had not worked out.

The babies born to exercising mothers continued to have lower heart rates and greater heart-rate variability four weeks after delivery than the babies born to the other women.