Group Based Dietary Interventions May Be Effective in Limiting Large-for-Gestational-Age Newborns and Gestational Weight Gain Among Obese Women

Resident Focus - Volume 10, Issue 1

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Reference: Obesity (Silver Spring) 2014 Sep;22(9):1989 (level 2 [mid-level] evidence)

Excessive gestational weight gain has been shown to amplify the risks of fetal macrosomia, increased childhood body fat, elevated blood pressure, and higher childhood BMI (Obstet Gynecol 2011 Apr;117(4):812). Approximately 30% of women of reproductive age are obese in the United States (Institute of Medicine and National Research Council. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: The National Academies Press; 2009). Over half of obese pregnant women gain more than the recommended weight gain during gestation. Dietary counseling and weekly participant contact have been the most effective weight loss and weight maintenance interventions in non-pregnant adults. Few interventions with less frequent direct participant contact have been successful in limiting gestational weight gain among obese nondiabetic pregnant women. Is a weekly, group based weight management intervention focused on diet and behavior changes effective in limiting gestational weight gain among obese women, and thereby reducing the percentage of large-for-gestational-age (LGA) infants?

This randomized controlled trial studied women receiving prenatal care at Kaiser Permanente Northwest between the years of 2009 and 2011. The authors enrolled 114 women with a BMI greater than or equal to 30 kg/m2, age 18 and older, and English speaking, in a parallel group design with a 1:1 allocation ratio. Women with diabetes mellitus or other medical conditions requiring specialized nutritional care as well as women with plans to leave the area during follow up were excluded. Participants completed baseline questionnaires and were randomized using a computerized algorithm which stratified subjects based on age ( <30 and 30 and older) and BMI (30-34.9 kg/m2, 35-39.9 kg/m2, and 40 or greater kg/m2). The intervention group was provided with a combination of exercise (at least 30 minutes of moderate physical activity per day), dietary recommendations (DASH diet without sodium restriction and with personalized calorie goals) and behavioral self- management techniques to help initiate and maintain behavior changes. The goal was to help participants maintain their weight to within 3% of their weight at randomization. Intervention participants received 2 individual counseling sessions to tailor the diet and exercise program to meet the individual’s needs, then the participants attended weekly group sessions which included education on nutrition and/or exercise, behavior change, and goal-setting. Women monitored their progress by keeping a journal of food, physical activity, and weekly weight charts. In contrast, control participants received a one-time dietician advice session regarding eating healthy during pregnancy (no DASH diet or weight management). Total gestational weight gain (weight measured at 2 weeks postpartum minus baseline weight) was the primary outcome. Rate of weight gain was stratified into “above” (> 0.6 pounds/week), “within” (0.4-0.6 pounds/week) and “below” (<0.4 pounds per week) the 2009 IOM guidelines for weight gain during pregnancy. 93 women completed the program.

In the intervention group, the mean weight declined by 2.6 kg between baseline and 2 weeks postpartum, and increased by 1.2 kg in the control group (mean difference 3.8 kg, p < 0.001). Intervention participants gained less weight (5.0 vs 8.4 kg, p < 0.001) and had a lower weight gain rate (mean difference 0.18 kg/wk, 95% CI [0.26 to 0.09]). Of particular interest, 9% of the intervention group vs. 26% of the control group gave birth to LGA neonates (p = 0.02). There were no differences in small-for-gestational age (SGA) neonates and a nonsignificant reduction in macrosomia (11% vs. 22%, p=0.09). In addition, 18% of the 56 women in the intervention group maintained their weight to within 3% of their baseline weight and 9% lost weight. No differences were found between the two groups in preterm birth, neonatal intensive care unit admission, respiratory morbidity, neonatal hyperbilirubinemia or hypoglycemia. One limitation of this trial is the lack of an attention control.

Weekly group sessions to aid in weight management in obese pregnant women are effective in limiting large-for-gestational age infants and gestational weight gain without increasing the risk of small-for-gestational age infants. Although previous studies have shown individual and frequent participant contact to be effective, this is the first study to demonstrate weekly group sessions to be effective and less resource intensive. However, a larger study with adequate power is needed to ensure that there are no increased risks of SGA or other adverse outcomes in the intervention group.

For more information, see the Routine prenatal care topic in DynaMed.