The primary aim of this study is to evaluate whether a lifestyle intervention of diet, exercise, and breastfeeding is associated with decreased postpartum weight retention and reduced plasma glucose levels, measured at 6-weeks and 1-year postpartum, among women with gestational diabetes mellitus (GDM). Secondary outcomes are postpartum levels of plasma insulin, markers of insulin resistance, adiponectin, dietary fat, physical activity, and breastfeeding duration.

Postpartum predictors of type 2 diabetes incidence in women with GDM are pregnancy weight retention and postpartum weight gain. By promoting physical activity and appropriate diet during pregnancy and soon after delivery, and preventing excessive pregnancy weight gain and postpartum weight retention, the postpartum incidence of obesity and type 2 diabetes might be reduced or delayed in GDM women. We are implementing and evaluating a lifestyle intervention of diet, physical activity, and breastfeeding among women with GDM. The diet and physical activity elements of the intervention are similar to the DPP-Follow-up study. All participants have GDM by plasma glucose levels measured during a standard 100-g, 3-h OGTT according to the ADA and the ACOG criteria and have no contraindications to participating in a diet and physical activity program. At study entry, eligible women are randomly assigned to life-style intervention or usual medical care. The intervention starts during pregnancy and continues for one year postpartum. It consists of structured, individually tailored, in-person sessions and telephone calls with a lactation consultant and a life-style coach. The goals of the intervention during pregnancy are to help GDM women comply with the Institute of Medicine guidelines for weight gain by following the ADA and ACOG recommendations for physical activity and diet. After pregnancy, the goals of the intervention are to help women exclusively breastfeed for at least six months and reach their pre-pregnancy weight. For those women who were overweight or obese prior to pregnancy, the additional goal of a reduction in weight of at least 5% of their pre-pregnancy weight is also set. For the maintenance phase of the intervention, beginning at 8 months postpartum, the intervention women receive tailored written materials in the mail and telephone calls reinforcing the positive changes they have adopted. All participants have follow-up clinic visits at 8-week, 8-month, 12-month, 18-month, and 24-month after delivery. Data analyses will be by intent-to-treat. Demographics, psychosocial and behavioral factors that may be related to success at achieving the postpartum weight goals and the secondary postpartum outcomes will be examined.

Inclusion Criteria:

• Diagnosis of Gestational Diabetes Mellitus

Exclusion Criteria:

• Ever diagnosed with diabetes when not pregnant
• Ever diagnosed with cardiovascular disease
• Ever diagnosed with lung disease
• Hemoglobin < 9.5 mg/dl
• Hematocrit less than 30%
• SBP >= 140 or DBP >= 90 in the last month
• Diagnosis of thyroid disease in the last month