By Colleen Zewe
Medill Reports

Many pregnant women struggle with weight gain, but those who begin pregnancy overweight or obese risk developing diabetes, high blood pressure and other serious prenatal conditions that can cause harm to their unborn babies.

Many of these women fear harming their unborn babies if they gain too little during pregnancy. But a recent Northwestern medical study helped pregnant, overweight women limit their weight gain, and found that obese or overweight women can safely restrict their calories to prevent health conditions without causing harm to themselves or the baby.
Published in the American Journal of Preventive Medicine, the Maternal Offspring Metabolics: Family Intervention Trial (MOMFIT) introduced pregnant women to the “Mama-DASH” diet, a slight modification of the popular Dietary Approaches to Stop Hypertension.

“The DASH diet is incredibly nutritious,” said Linda Van Horn, lead researcher and professor of preventive medicine at the Feinberg School of Medicine. “The DASH diet is ideal for pregnant women, as well as for obese or overweight pregnant women who are more at a risk for developing gestational hypertension.”

Van Horn said the diet allows for low-fat dairy, which pregnant women need for the vitamin D and calcium benefits, making this diet more ideal than others.

Nutritionists traditionally use the DASH diet to prevent hypertension, or high blood pressure. For pregnant women, gestational hypertension can turn deadly.

Gestational hypertension can lead to preeclampsia, and according to the Mayo Clinic, complications include premature birth, fetal growth restriction, seizures, cardiovascular disease and organ damage. Pregnant women must try to control their blood pressure, Van Horn said.

“The hope is that by controlling diet and weight gain, hypertension can be controlled,” Van Horn said.

Other nutritionists agree that the DASH diet is safe for pregnant women.

“The type of diets that I would recommend to a pregnant mom with obesity would either be the DASH diet or a Mediterranean-style diet,” said Michelle Cardel, director of the Obesity Research Alliance at the University of Florida. “Neither of these diets are overly restrictive, and they both place a focus on increased fruit and vegetable intake, healthy sources of fat such as nuts and lean sources of protein.”

The 281 participants were divided into intervention and control groups. The intervention group tracked their food using a convenient nutrition-tracking app, and their nutritionist also had access to their inputs. They also used a pedometer and received group nutrition sessions and personal nutrition coaching.

The study found no difference in newborn weight between the two groups, though the intervention group reported lower gestational weight gain. Women in the intervention group gained an average of 22 pounds, while women in the control group gained an average of 26 pounds. There was also no difference in blood pressure.

The amount of weight a woman should gain during pregnancy depends on her pre-pregnancy weight. Van Horn said that, while weight loss is never recommended during pregnancy, those who begin pregnancy at a high weight should restrict their overall weight gain.

Weight gain can vary, however, for women in any group, and is an issue to discuss with the obstetrician. According to American Pregnancy, women must gain some weight during pregnancy to provide nourishment to the baby and to store energy for breastfeeding.

“On average, we don’t tend to need any additional calories during the first trimester, about 300 extra calories in the second trimester, and approximately 450 more calories per day in the third trimester,” Cardel said. “For the second trimester, that equates to the same amount of calories that are in a small handful of nuts and an apple. Tracking calories can help patients self-monitor their calorie intake to ensure that they are staying within the recommended guidelines, making sure they are not eating too much or not enough calories.”

Because of the health risks, those who begin their pregnancy at a higher BMI should gain less weight than others. However, doctors often leave women to navigate pregnancy weight gain on their own.

Elisa Lancaster, of suburban Geneva, was obese during her pregnancies in 2015 and 2017,  but her doctors did not give her advice on limiting weight gain, she said.

“They made mention of the risk of preeclampsia, but not much,” said Lancaster, 32. “They said, ‘hey, you shouldn’t gain too much weight,’ but kind of left it at that. They didn’t give me much direction. They just said have a balanced diet.”

Lancaster, who did not develop preeclampsia, acknowledged that for many pregnant women, going on a strict diet plan during pregnancy could be difficult due to nausea.

“You’re really just trying to function,” she said. “I work full-time, so in addition to all of those nausea symptoms, I had to function at work, so my diet was not at the forefront of my mind.”

Of course, adults are not the only people who struggle with their weight.

“The next big question is whether the children born to moms who restricted their weight gain will have a reduced risk of becoming obese themselves compared to children whose moms were in the control group,” Van Horn said in a press release.

Van Horn now hopes to prevent obesity in the children of obese and overweight moms, and is recruiting for a study called KIDFIT. The study will involve many moms who participated in MOMFIT, but the intervention and control groups will be re-randomized, giving new moms a chance to receive nutrition coaching.

“Our goal with KIDFIT is to further intervene on children who are at risk at being overweight or obese because their moms were overweight or obese,” Van Horn said. “We are trying to further the mom’s knowledge and understanding of the DASH diet to help their children avoid excess weight gain.”