"Despite what we have said over the last 10 years, pregnant women are still afraid exercise is going to hurt their child," says researcher Melissa J. Hague, MD, a clinical assistant professor of obstetrics and gynecology at the University of Kansas School of Medicine in Wichita.
In her study of 90 women, she found many regular exercisers stopped working out when they became pregnant. Some told her they did not think exercising, even walking, was safe during pregnancy.
"I was really surprised," she tells WebMD.
Hague presented her findings this week at the annual meeting of the American College of Obstetricians and Gynecologists (ACOG) in San Diego.
In 2002, ACOG issued an opinion about exercise during pregnancy. Recreational and competitive athletes without pregnancy complications can remain active with their doctor's OK, it says. They should modify their workouts as medically indicated.
Inactive women should consult their doctors before starting a program, it says.
Moderate exercise for 30 minutes or more most or all days of the week appears safe for pregnant women without complications, it says. Activities with a high risk of falling, contact sports, and scuba diving should not be done.
Exercise During Pregnancy: Study Details
Hague cares for pregnant women in her practice. She was curious as to why so many do not exercise.
She and her team did phone interviews with 90 women. They were 16 to 30 weeks pregnant.
Before becoming pregnant, almost half of the women said they exercised moderately at least 90 minutes a week.
After becoming pregnant, less than 27% did. "They said they were afraid they were going to hurt the baby," Hague says.
Safety concerns were more of an issue with those who weren't active, Hague found.
About 62% of those who exercised during pregnancy thought working out longer than 30 minutes is safe.
Only 18% of those who did not exercise thought so.
Hague found ethnic differences in attitudes toward exercise during pregnancy:
Nearly 89% of white women said brisk walking is safe during pregnancy, and 90% said swimming is safe.
Only 60% of other ethnic groups thought brisk walking is safe, and only 67% thought swimming is.
Myths passed down within the family may trigger women's fears, Hague tells WebMD. "If the moms tell them, 'You are going to hurt the baby,' they are not going to do it," she says of exercise during pregnancy.
Certain women were more likely to exercise during pregnancy, including those who believed they could manage it despite a busy schedule. Those who worked outside the home were more likely to fit in exercise during pregnancy.