There is more medical evidence that pregnant women should steer clear of advice to “eat for two.”

Alison Stuebe, M.D., assistant professor of obstetrics and gynecology at the University of North Carolina at Chapel Hill School of Medicine, reviewed data for more than 1,300 women and found that those who consumed extra calories, as well as fried foods and dairy products, were more likely to gain more than is recommended during pregnancy – that’s 35 pounds or more for a woman with a normal body mass index, or BMI.

Stuebe found that eating an extra 500 calories a day increased the odds of gaining too much by 10 percent. “That’s the number of calories in a muffin or a bagel with cream cheese at Dunkin Donuts,” Stuebe says. “It doesn’t take much for the calories to add up.”

Gaining too much weight is linked with complications at birth, such as pre-eclampsia or requiring a C-section, as well as higher odds that both mom and child will be obese later in life.

But the study results are good news – there’s something women can do to reduce risks for themselves and their babies. “It’s a two-fer,” Stuebe says. “If you take care of yourself, it’s good for you and for your baby.”

Several eating habits reduced moms’ risk of gaining too much. Women with vegetarian diets in early pregnancy were half as likely to gain an unhealthy amount of weight, and those who exercised vigorously for a half hour a day reduced their risk by 20 percent. The researchers also found that consuming more monounsaturated fat, found in olive oil and nuts, was linked with a lower risk of excessive weight gain.

Stuebe did the research while at Brigham and Women’s Hospital in Boston. The results were published May 19, 2009, in the online version of the American Journal of Obstetrics and Gynecology (available to subscribers).

It might be obvious that a healthy diet and exercise reduce the odds of gaining too much weight during pregnancy, but more and more women are doing just that. Part of the problem is that providers don’t counsel moms on weight gain, Stuebe says. Other studies have shown that moms who get advice from their doctor or midwife are more likely to gain in a healthy range.

Stuebe’s study offers some guidelines to share with expecting moms. Eating fried foods “was a huge predictor of excessive weight gain,” she says. Women who ate one serving a day were four-times as likely to gain too much weight.

Some study results were surprising. For example, dairy products, including those made with low-fat milk, were associated with more weight gain. More studies are needed to sort out why milk products were associated with extra gain.

The study used data from Project Viva, a prospective cohort of mothers and babies in the Boston, Mass., area. The study is ongoing, and researchers are currently following up the children at age seven.

For now, Stuebe says, her study results offer guidelines for moms to make healthy choices during pregnancy. “The next step is to study whether moms who get this advice have healthier weight gain than those who do not,” she says.

In the meantime, moms should follow existing guidelines to get regular exercise, and avoid fried foods and high-calorie snacks. Otherwise, after childbirth, they may find themselves struggling to unload extra pounds.

“And losing for two is a lot of work,” Stuebe says.

Source: University of North Carolina at Chapel Hill School of Medicine