Exercise during pregnancy good for mom, baby

The consensus on exercise during pregnancy is now clear: It can benefit overall health, help manage weight and lead to fewer aches and pains.

But many women remain understandably confused.

“For too long we have told pregnant women in this country to eat for two and limit their activities,” says Raul Artal, chairman of the department of obstetrics, gynecology and women’s health at St. Louis University School of Medicine.

Exercise has no effect -- positive or negative -- on a fetus, says Artal, a coauthor of guidelines published by the American College of Obstetricians and Gynecologists in 2002. But “the fetus will benefit in general from a healthy mother.”

The organization suggests that pregnant women with no medical or obstetric complications follow the government’s advice for most adults: Get at least 30 minutes of moderate exercise on most days of the week. There are, of course, caveats.

* Heart rate: Old advice said pregnant women should keep their heart rates below 140 beats per minute. “That was never based on sound science,” says Hope Ricciotti, a clinician and associate professor of obstetrics, gynecology and reproductive biology at Harvard Medical School. “Just listen to your body,” Ricciotti says. “Stop if you feel dizzy or very short of breath.”

* Body heat: If a woman is properly hydrated, Ricciotti says, the body heat generated by moderate exercise is no threat. But Artal urges caution, since studies show that more extreme overheating can cause neural tube defects.

* Impact: Avoid exercise that risks abdominal impact in the second and third trimesters. Such activities include soccer, hockey and basketball, and sports with a fall risk.

* Position: During the second and third trimesters, do not exercise while lying on your back. That compresses the inferior vena cava blood vessel, limiting blood flow to the fetus. This applies to certain moves in weight training, yoga and Pilates.

* Intensity: Many pregnancy websites advise against strenuous exercise, but Ricciotti and the obstetricians group say there are no data showing harm.

* Exceptions: The guidelines list contraindications such as heart or lung disease; incompetent cervix/cerclage; persistent second- or third-trimester bleeding; and early labor. Among signs calling for immediate cease-and-desist and doctor consult: vaginal bleeding, dizziness, headache, chest pain, calf pain or swelling or amniotic fluid leakage.