Pregnancy can drain your energy, especially during the first trimester. Some women experience bouts of nausea that make exercise seem like an impossibility. Even on good days you may rightfully worry that certain types of exercise could endanger your growing baby. But being pregnant doesn’t mean you have to sit around on a couch all day eating bon-bons (thought that does sound somewhat appealing!). In fact, getting regular exercise throughout pregnancy—at least 30 minutes a day—can improve sleep, increase your energy level during waking hours, alleviate back pain, reduce constipation, bloating and swelling, and keep your muscles strong and toned as you prepare for childbirth. And despite what you may think, running during pregnancy can be perfectly safe and even beneficial.
In a Runner’s World article from October 2010, New York obstetrician Kathryn Peck Rutenberg offered reassurance for pregnant runners. “Each woman and each pregnancy is different,” she said, “but if there are no complications, runners can keep running.”
While it is certainly okay for runners to keep running, women generally should not begin a running regimen after becoming pregnant. Talking with a health care practitioner before beginning any exercise program is advisable.
The American Congress of Obstetricians and Gynecologists (ACOG) has said that running during pregnancy may be safe if you were a pre-pregnancy runner. Rutenberg noted that, while you can continue running the same amount as you did pre-pregnancy, you should do so at a slower pace during pregnancy. A 10-minute miler may slow down to a 13- or 14-minute pace per mile and still feel equally challenged.
A number of factors contribute to the need to slow down during pregnancy. Physiologically, a pregnant woman experiences an increase in blood volume of 30 to 50 percent, allowing her to share oxygen and nutrients with her baby. This increased blood volume requires the heart to work harder; with a higher resting heart rate, exercise needs to slow down in order to keep within a safe heart rate range.