Workout-Tips-Second-Trimester-14-pg-fullGretchen Reynolds cites a great reason why young people — especially young women — shouldn’t take their physical fitness for granted:

If a woman is physically active during pregnancy, she may boost the development of her unborn child’s brain, according to a heart-tugging new study of expectant mothers and their newborns. The findings bolster a growing scientific consensus that the benefits of exercise can begin to accumulate even before someone is born.


Researchers at the University of Montreal recruited pregnant women in their first trimester to participate in this study.  Prior maternal history and attitudes about fitness were not relevant: the study looked at the effects of exercise only during pregnancy on babies’ health after birth:

All were healthy, young adults. None were athletes. Few had exercised regularly in the past, and none had exercised more than a day or two per week in the past year.

Then the women were randomized either to begin an exercise program, commencing in their second trimester, or to remain sedentary. The women in the exercise group were asked to work out for at least 20 minutes, three times a week, at a moderate intensity, equivalent to about a six or so on a scale of exertion from one to 10. Most of the women walked or jogged.


Once the babies were born, their brain waves were tested in response to auditory stimuli.  You can probably guess the outcome:

In this case, the relevant brainwave activity soared in response to the novel sounds among the children born to mothers who had remained sedentary during pregnancy. But it was noticeably blunted in the babies whose mothers had exercised. In essence, “their brains were more mature,” Ms. Labonte-LeMoyne said.


This study provides an example of how modest exercise during pregnancy (with the blessing of an obstetrician, of course) has a positive effect on a young baby’s brain development.  I would guess the moms also benefited from their exercise regimens themselves.  While the study shows it’s not too late for sedentary women who get pregnant to get moving, it’s a lot easier to be active as an adult — man or woman — if you are already used to it!