It's become common for pregnant women to be told that they're eating for two. But is that really necessary?
Not only is it unnecessary, but it could be dangerous for women who are overweight, according to researchers involved in the first clinical trials to help obese moms-to-be to control their weight during pregnancy.
The study by the Kaiser Permanente Center for Health Research aims to avoid the complications commonly associated with obese moms-to-be such as high blood pressure, diabetes, bigger babies, C-sections and birth injuries.
More than half of women in the United States are overweight or obese when they become pregnant, and most go on to gain more than the recommended amount during pregnancy, according to Kaiser Permanente.
Current guidelines suggest that women of normal weight gain between 25 and 35 pounds during their pregnancy, and suggest an 11- to 20-pound weight gain for obese women.
Study researchers acknowledged that their investigation was a challenge to national guidelines.
"It is counterintuitive, I think particularly in our culture, where eating for two has become a common concept," said Dr. Kim Vesco, an obstetrician/gynecologist who is directing the ongoing study. "We're asking pregnant women to stay within 3 percent of their baseline weight. So, for a 200-pound woman, that would be six pounds."
Jamie Martin of Portland, Ore., gained more than 40 pounds in her first pregnancy, so she thought the goals of the Healthy Moms study would be impossible for her.
"You're taking women like me, notorious for gaining more than they're supposed to. And now you're saying to go to the other extreme," she said. "And you go, 'wow, I don't know if I can do that.'"
But it's critical that obese women try.
"These women are already carrying between 50 and 100 extra pounds -- and for them any more weight gain could be very dangerous," said Vic Stevens, a research psychologist and principal study investigator.
Last year the trial enrolled 180 obese pregnant women from Washington state and Oregon.
The study is still recruiting pregnant women.
Participants are all members of the Kaiser Permanente health plan, and they will be followed throughout their pregnancies and beyond to find out how much weight they gained, how large their babies were, how the babies grew and how they were fed, whether the women had birth complications and how much weight they kept on one year after giving birth, among other study objectives.
Preliminary results are expected in three years, but researchers believe the outcome will be that participants will have controlled their weight and delivered healthy babies.
Jamie Martin has already seen remarkable results.
At 7 ½ months pregnant, she has only gained 6 pounds. At this point in her last pregnancy, she had already gained 35 pounds.
"The first couple of weeks I had to really, really focus," Martin said. "And then, as I started to feel healthier and better, I started to get more of the fruits and vegetables in. And it just got progressively easier," she said.
Martin is allowed only 2,000 calories a day. She attends weekly nutrition sessions and keeps a food diary, helping her fight cravings.