Oct. 1, 2008 -- Women who diet before pregnancy tend to gain too much weight
Even women who succeed in controlling their weight before pregnancy tend to
gain too much weight while they're carrying a child, say Anna Maria Siega-Riz,
PhD, RD, and colleagues at the University of North Carolina at Chapel Hill.
"When they are not pregnant, many women are really trying to hold their
weight down. But when they become pregnant the message they get is 'Eat for
two; give in to your cravings,'" Siega-Riz tells WebMD.
The UNC researchers asked 1,223 women who had just become pregnant about
their previous dietary habits. About half the women had restrained their eating
habits in some way. They simply cut back on what they ate, followed specific
diet plans, and/or cycled between gaining and losing weight.
Regardless of how they did it, all normal-weight, overweight, or obese women
who had tried to restrict their diets gained more weight during pregnancy than
did women who did not diet before pregnancy.
Moreover, the pre-pregnancy dieters gained more weight during pregnancy than
doctors recommend -- putting themselves and their babies at risk.
Women who gain too much weight during pregnancy have more C-sections, more
preeclampsia, and are more likely to have babies with growth problems, says
obstetrician J. Christopher Glantz, MD, MPH, director of the perinatal outreach
program at the University of Rochester Medical Center.
"You might think people who are dieting before pregnancy would tend to
gain less weight. Not only is that not true, this study shows that in pretty
much all weight categories, the restrained eaters seem to gain more weight once
they get pregnant," Glantz tells WebMD.
Surprisingly, normal-weight women don't need much more food once they're
It's a different story only for women who are underweight before pregnancy,
but who restrict their diets anyway. These women, Siega-Riz and colleagues
found, did not gain enough weight during pregnancy -- and many likely suffer
from eating disorders.
"Pregnancy doesn't require you to eat that much more calories -- just an
extra glass of milk and an apple during the last two trimesters," Siega-Riz
says. "But you have to make sure you are eating a nutrient-dense, healthy
diet and not becoming physically inactive."
Glantz says the findings suggest that women, especially those whose weight
goes up and down, may not have a good internal sense of how much food they
"In these cases, it would be important to have a nutritionist meet with
these patients, because most obstetricians -- including me -- don't have the
training to know what specifically to recommend," he says.
"The amount of weight you gain during pregnancy is important for the
health of your child and for your own future health," Siega-Riz says.
"A lot of women think, 'I will just gain anything and just get it off
later. That doesn't happen, because it is really hard to lose
weight in the postpartum period."
The study appears in the October issue of the Journal of the American