The main goal of this study is to examine the comparative effectiveness of diabetes prevention strategies in women with Gestational Diabetes Mellitus (GDM) on the control of the following conditions: obesity, hyperglycemia, hypertension and depression. This randomized lifestyle intervention study will be conducted at Kaiser Permanente Northern California. Women in the intervention will receive a letter on gestational weight gain during pregnancy and in the postpartum period, a curriculum of individualized lifestyle counseling via telephone, augmented with e-mail and an interactive Web site. Patients randomized to the usual care arm will receive the standard-care telephone calls from the Perinatal Center during pregnancy and the Center's printed educational materials postpartum. Outcomes will be assessed through the electronic medical record and patient surveys conducted during pregnancy and at 6-weeks, 6- months and 1-year postpartum.

Inclusion Criteria:

All women, 18 years of age or older, receiving medical care at Kaiser Permanente Northern California with a pregnancy complicated by gestational diabetes between March 2011 and May 2012 that have a telephone or cellular phone will be eligible.

Exclusion Criteria:

Women with overt diabetes not recognized prior to pregnancy (any women with fasting plasma glucose > 126 mg/dl, or any plasma glucose level over 200 mg/dl on more than 1 occasion during pregnancy) will be excluded from the analyses but will be eligible for the lifestyle intervention.