Several research studies have suggested that mothers who exercise more during pregnancy give birth to babies who themselves are more likely to be active as children. A animal research study just published showed that pregnant mice who exercised on a running wheel produced mouse children who were about 50% more physically active than pregnant mothers who did not exercise.
Of course it is best to carry out experiments in humans, but often—and especially in the case of studies during pregnancy—this is not practical or safe, so animal studies are done instead. The results of many animal studies are thought to be relevant to human beings as well, as in this study.
This study was carried out by biologists and genetic scientists at the Baylor College of Medicine in Houston, Texas. The way they studied this was to take a group of genetically identical pregnant female mice and divide them into two groups. Half of the mice were kept in cages with a standard exercise wheel, and mice love to run on them, even while pregnant. The other half were in the same type of cages during their pregnancy, but the wheels were locked, so they could not run.
After the pregnant mice gave birth, and their babies were weaned, all the young mice were outfitted with miniature activity monitors, so their exercise levels could be accurately measured. They were all put into separate cages with running wheels that were unlocked, so they could run as much as they desired.
The young mice whose mothers were allowed to run freely during pregnancy turned out to be enthusiastic runners themselves when they entered the equivalent of mouse “adolescence”. And even while they were not running on their wheels, they moved around more than the mice born of the mothers who were sedentary.
Also, the mice born of sedentary mothers had much less interest in the running wheels. Interestingly, the differences between the two groups increased as the mice became older. In their “middle age”, the mice born of the active mothers became even more active than the other group of mice, even though they were all genetically identical.
This study is in the new area of research called “developmental programming”, which analyzes the how differences in diet, lifestyle, and activity during pregnancy can change the characteristics of the children born to these mothers. As in this mouse study, these differences can persist even into middle age and beyond.
How exercise during pregnancy may act on the genes
The theory is that different activities during pregnancy cause differences in secretion of various hormones and other chemicals secreted, and some of these cross through the placenta and can change how the DNA is “expressed” after birth and into adulthood. The genes in DNA can either be switched “on” or “off” depending on these hormones and other chemical factors.
Again, this study does not mean that pregnant women should take up running if they want to have athletically active children, but it does suggest that. This fits in with the advice of many obstetricians today that pregnant women do better and deliver healthier babies if they are physically active. The best advice is to talk to your obstetrician to see what activity level is best for you.
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