(Reuters) - Compared to obese expectant mothers without special care, those given individualized calorie goals and weekly group meetings gained less weight during pregnancy and had fewer oversized newborns in a new study.
"More than half of women in the U.S. start out their pregnancies overweight or obese, and approximately half of all pregnant women gain too much weight during pregnancy, which can lead to increasing overweight and obesity," said the study's lead author Dr. Kimberly K. Vesco of the Center for Health Research at Kaiser Permanente, Northwest, in Portland, Ore.
"Women who gain too much weight during pregnancy may retain some of that extra weight and enter their next pregnancy at a higher weight than their prior pregnancy, which can increase their risk for pregnancy complications such as gestational diabetes, high blood pressure, babies that are too big and cesarean section," Vesco, a board-certified obstetrician-gynecologist, told Reuters Health by email.
The U.S. Institute of Medicine, a government advisory body, has issued guidelines for healthy amounts of weight gain during pregnancy, although they remain controversial (see Reuters Health story of November 17, 2010, here: reut.rs/1AXzmJz).
The guidelines suggest that normal-weight women gain around 25 pounds during pregnancy but that obese women limit their weight gain to between 11 and 20 pounds.
For the new study, rather than giving obese women the IOM target range, Vesco's team asked 114 of them to try to maintain their weight at the start of the study, which was early in pregnancy, and assumed the women would gain a little weight anyway.
Vesco and her team divided the participants, who were all obese and at least seven weeks pregnant when recruited into the study, into two groups. Women in one group received a single advice session from a dietician with general information about eating a healthy diet during pregnancy and usual care for the rest of their pregnancies.
The second group attended two individualized counseling sessions where the dietician gave each woman tailored diet and physical activity guidelines, recommending at least 30 minutes of moderate activity each day, geared toward helping them gain no more than three percent of their current body weight throughout pregnancy.
For a 200-pound woman, that would mean gaining no more than six pounds.
Once they had their individual goals, the women started attending weekly 90-minute group sessions covering topics including nutrition, exercise and behavioral change. They were also given a goal for physical activity in the next week. The women kept food and activity journals and tracked their weight each week.
By week 34 of pregnancy, women in the weight-control group had gained an average of 11 pounds and women in the comparison group had gained 18.5 pounds.
By two weeks after giving birth, moms in the weight control group were an average of almost six pounds lighter than when they enrolled in the study, whereas in the comparison group moms were an average of 2.6 pounds heavier.
Nine percent of babies born to mothers in the weight-control group were large for their gestational age - which increases the risk of birth injury and infant low blood sugar - compared to 26 percent of babies in the other group, according to the results published in the journal Obesity.
"A common misconception during pregnancy is that women need to eat for two," Vesco said. "That's just not true. Most pregnant women need no extra calories in the first trimester and only 200-300 extra calories in the second and third trimesters.
"Our study found that limited or no weight gain may be beneficial for mom and baby, but we still need larger studies to confirm these findings before the IOM guidelines can change."
Doctors can help women control their pregnancy weight by weighing them, calculating their body mass index and giving them weight-gain targets for pregnancy, said Dr. Alexis Shub, a senior lecturer in the department of obstetrics and gynecology at the University of Melbourne in Australia.
"In our own research we have found that many obese women do not recognize that they are obese, and many overestimate the appropriate weight gain for pregnancy - so education by health care professionals is very important," she told Reuters Health by email.
"It is laudable that research is taking place to answer questions that affect so many women and babies that we see every day in clinical practice, and that managing weight gain for these women may have a long term role in their own health and the health of their children," said Shub, who was not involved in the study.
But, she noted, more than 1,000 women declined to be in the trial, so those that participated were highly motivated. A less motivated group would likely have been less successful, she said.
Most women, not just those who are obese, can benefit from setting a weight- gain goal and following a healthy eating plan, Vesco said.
Implementing this approach, with 90-minute weekly meetings and behavioral specialists, could be done in the real world, but it would require ongoing resources and commitment from a health plan, and it's unclear how much it would cost, she said.
"Women who are obese when they get pregnant should talk to their practitioner and together set their weight gain goals," Vesco said. "They can seek dietary advice from their practitioner or a dietician."
