Exercise during pregnancy appears to be safe even for African-American women at high risk for pregnancy complications, a new study suggests.

The study, which focused on poor, urban African-American women, found that “exercise participation did not increase or decrease the risk of low birth weight or preterm birth,” said co-author Suezanne Orr, Ph.D.

“There is not much information about exercise participation in this population. Most of the research has been on middle-aged white women,” said Orr, with the Department of Health Education and Promotion at East Carolina University, in Greenville, N.C.

The study, which appears in the current issue of the journal Ethnicity and Disease, looked at 922 low-income African-American women receiving prenatal care at five Baltimore clinics between 1993 and 1995.

Women in the study were 18 or older. Almost 30 percent reported having a chronic illness, such as diabetes or hypertension; nearly 20 percent had poor maternal weight gain during pregnancy and 32 percent had a previous pregnancy with a poor outcome.

During pregnancy, 56 percent of the women reported participating in nonstrenuous exercise, such as gardening or walking. Just 2 percent said they participated only in strenuous exercise, such as running or biking, while 6 percent participated in both levels of exercise. Almost 36 percent of the women got no exercise at all.

About 12 percent of the women had babies with low birth weight and 13.7 percent had babies who were born prematurely. However, researchers found no association with exercise and these outcomes.

“Even among women with chronic diseases or previous poor outcomes, exercise during pregnancy was not associated with either preterm birth or low birth weight,” the authors concluded.

Orr cautioned that the study focused on exercise for “fun and fitness,” and not on other types of physical activity, such as standing for work or climbing stairs. Some previous studies have shown these activities may increase chances of poor pregnancy outcomes for at-risk women.

“It’s actually possible there is a protective effect from exercise here. We know from other research that it’s unlikely that there is an adverse effect,” said Dawn Misra, Ph.D., of the University of Michigan School of Public Health in Ann Arbor.

However, Misra added that it’s not necessarily a good idea to recommend exercise for at-risk women. “I am not sure you can draw that conclusion based on the limited research that’s been done,” she said.

The American College of Obstetricians and Gynecologists advises that healthy pregnant women can engage in 30 minutes of moderate exercise most days of the week. However, with the lack of information about the effects of physical activity in pregnant women with chronic diseases, broad recommendations have not been made for this group.