For obese people, food is a habit. They associate a movie with chips or cake and a movie is not a movie without the snack. Taken out of their routines, people quickly unlearn such habits.

Nothing overturns routine like pregnancy - and that may a great inroad to better health. Results presented this weekend at the joint meeting of the International Society of Endocrinology and the Endocrine Society (ICE/ENDO 2014 in Chicago) found that obese pregnant women who adhere to an intensive nutritional and exercise program starting in the first trimester gained less weight and had fewer pregnancy complications compared with peers who receive standard prenatal care.

Obesity is a risk factor for pregnancy complications, such as gestational diabetes and pre-eclampsia, which is high blood pressure and protein in the urine. It also increases the risk of having an infant who is large for gestational age (birth weight greater than the 90th percentile adjusted for gestational age) or who has macrosomia, a birth weight exceeding 8 pounds, 13 ounces (4,000 grams). A high-birth-weight baby raises the risk of needing a cesarean section.

The study enrolled obese Chinese women who were six to 12 weeks pregnant (first trimester) and randomly assigned them to receive either standard care (72 women) or the intensive program (141 women), both of which included visits to the obstetrician. Standard care consisted of one group session with a dietitian, who discussed proper nutrition, physical activity and recommended pregnancy weight gain.

The other group participated in one group session followed by individual counseling tailored for each subject regarding regular exercise and eating a balanced diet between 1,500 and 2,000 calories a day. Subjects were asked to record what they ate, their physical activity and their weekly weight gain, and this information was used to modify the plan for each individual.

"Obese pregnant women should start an intensive intervention involving dietary and lifestyle modifications as early as possible in pregnancy," said lead investigator Guanghui Li, MD, PhD, associate professor, Department of Obstetrics, Capital Medical University, Beijing.

Of the 141 women in the program, 68 adhered to the recommendations and 73 did not, which Li said indicated how difficult it is for obese women to modify their lifestyles. "Health care providers should pay more attention to make practical and effective intervention strategies for obese pregnant women to enhance their compliance with the recommendations," she said.

According to Li, women who complied with the recommendations had significant benefits compared with the other study participants. Throughout pregnancy, they gained an average of 24 pounds (10.83 kilograms, or kg). Both the non-adherent group and standard-care group gained just over 31 pounds (14.13 and 14.10 kg), on average. Weight gain was less in the adherent group before and after an oral glucose tolerance test performed between 24 and 28 weeks of pregnancy to check for gestational diabetes.

In addition, no one in the adherent group developed mild pre-eclampsia, versus 2.7 percent of the non-adherent group and 6.9 percent of the standard-care group, study data showed. The intervention did not harm fetal growth or lead to any maternal or fetal complications, Li stated. In fact, she said it reduced the chance of having an abnormally large baby. 

The reported macrosomia rate was 7.4 percent in the adherent group versus 27.4 percent in the non-adherent group and 25 percent in the standard-care group. Rates for large-for-gestational age infants were 10.3 percent in the adherent group versus 32.9 percent and 25 percent for the other groups.