For millions of women, exercise is an integral part of their busy day, but how safe is panting and perspiring during pregnancy?
New research suggests that some exercises need to be curbed or even avoided during pregnancy, while others are being recommended right up through the early stages of labor.
"Women who are exercising don't want to take nine months off to have a baby," said Dr. Mona Shangold, director of the Sports Gynecology Center at Georgetown University. "And there are really good reasons why women should continue exercising throughout their pregnancy.
"But we need to give (women) some important guidelines so that their activity doesn't endanger the baby," she said.
The theoretical risks of exercise to both mother and fetus include premature labor, cardiovascular complications, musculoskeletal injuries, congenital malformations or defects and growth retardation.
Study May Take Two Years
However, Dr. James Clapp, another leading researcher in the field, emphasized that that's all those risks are at the present time: theoretical.
"All the evidence is anecdotal and nothing that could be considered harmful (to the fetus) has been shown to date," he said.
The professor of obstetrics and gynecology at University of Vermont is currently conducting a study that may offer conclusive evidence, but it won't be finished for at least another two years.
Clapp's own past research has revealed that women who exercise throughout their pregnancy appear to gain less weight, recover faster and deliver babies that are "a bit lighter, but quite healthy."
These differences were seen only among women who continued exercising right through their pregnancy. "If you stop exercising at your third trimester, it's just as though you never exercised at all during your pregnancy," he said.
"Women who exercise throughout their pregnancy do deliver babies that are about a pound and a quarter lighter than mothers who didn't exercise," Clapp said. "That's the same effect seen in women who smoke two packs of cigarettes a day."
Before women gasp and swear off their aerobics, Clapp quickly added that there is a big difference between the two sets of patients; babies born to exercising mothers show none of the health problems seen in offspring who have shared their mothers' two-pack-a-day habit.
"These babies (of women who exercise) are a little less fat, that's all," he said.
If there are few proven risks to mother and baby, it doesn't necessarily follow that there aren't guidelines that should be followed when exercising for two.
For example, Dr. Raul Artal, an associate professor of obstetrics and gynecology at University of Southern California, concurred with Shangold and Clapp, but noted: "There are certain limitations, both anatomically and physiologically, which should preclude pregnant women from continuing the same exercise regimen during pregnancy that they maintained in their non-pregnant state."
First, Artal said, "If you don't exercise regularly, being pregnant is not the time to start."
Shangold added: "It's unfortunate that many women become interested in fitness and nutrition for the first time during pregnancy. They really should get in shape in order to become pregnant and then maintain that (level of fitness) during their pregnancies."
Center of Gravity Shifts
Artal noted that the best exercises are walking, swimming and stationary bicycling.
"The stationary bike is recommended because pregnant women undergo a change in their center of gravity during pregnancy, so they are more prone to losing their balance if they're riding a standard bicycle," he said.
"Basically, any type of soft aerobics is excellent for pregnant women," he said, noting that the jerky or bouncing movements of standard aerobic dance should be avoided.
For women not accustomed to aerobic exercise before pregnancy, Shangold suggests limiting activity to nothing more vigorous than brisk walking. For women who are involved in an aerobics program, she suggests continuing "at the same perceived level" of exertion.
"Your actual pace will have to be slower," she explained. "Merely being pregnant is more work for the body. Add in the extra weight that comes with carrying a baby, and you will be able to do less work to get to the same level of exertion."
There is one exception to Shangold's rule against initiating any type of exercise program during pregnancy.
"All pregnant women should be involved in weight-training programs," she said. "Even if you haven't been doing it before (the pregnancy), you should start."
A weightlifting regimen, according to Shangold, protects women from many of the muscular aches and pains that often accompany pregnancy.
This advice is contrary to popular belief regarding women and heavy lifting, but Shangold believes that "that's an old myth, which should be put to rest. All women should be engaged in weight-training exercise and pregnant women in particular can benefit from such an exercise program."