Pregnancy and EARly Lifestyle Improvement Study

Inclusion Criteria: * Singleton viable pregnancy. A twin pregnancy reduced to singleton before 14 weeks by project gestational age is acceptable. An ultrasound must be conducted before randomization that shows a fetal heartbeat; there should be no evidence of more than one fetus on the most recent pre-randomization ultrasound.\* * Gestational age at randomization no earlier than 9 weeks 0 days and no later than 15 weeks 6 days based on an algorithm that compares the last menstrual period (LMP) date and data from the earliest ultrasound.\* * BMI ≥25 kg/m2 based on first trimester measured weight and on measured height. The earliest weight measurement before randomization, measured specifically for the study will be used. Reported pre-pregnancy weight will not be used to determine eligibility because of the potential for inaccuracy. If the earliest weight measurement is conducted at 140 to 146 weeks or 150 to 156 weeks, 1 lb or 2 lbs will be subtracted from the measured weight respectively, to adjust to a first trimester weight.\* * Age ≥ 18\* Exclusion Criteria: * Diagnosis of diabetes prior to pregnancy (reported physician diagnosed diabetes other than GDM in previous pregnancy or taking insulin or medications to treat diabetes), or an HbA1c ≥ 6.5 % or other test result (elevated fasting glucose ≥126 mg/dL/7.0 mmol/L or 2 h glucose ≥200 mg/dL/11.1 mmol/L when OGTT is completed) suggestive of pre-pregnancy diabetes. All potential participants will have HbA1c performed prior to randomization.\* * Known fetal anomaly \* * Planned termination of pregnancy\* * History of three or more consecutive first trimester miscarriages\* * Past history of anorexia or bulimia by medical history or patient report. Binge eating disorder is not an exclusion\* * Current eating disorder diagnosed by EDE-Q questions 2-4 and confirmed after discussion with the participant by study staff\* * Actively suicidal defined as a value ≥ 2 on the BDI-II question 9\* * Prior or planned (within 1 year of expected delivery) bariatric surgery\* * Current use of one or more of the following medications: \* * Metformin * Systemic steroids * Antipsychotic agents * Anti-seizure medications or mood stabilizers that would be expected to have a significant impact on body weight * Medications for ADHD including amphetamines and methylphenidate * Continued use of weight loss medication including OTC and dietary supplements for weight loss \* * Contraindications to aerobic exercise in pregnancy specified in the ACOG Committee Opinion #267, 2002 (reaffirmed 2009) \* * Hemodynamically significant heart disease defined as an AHA class II (short of breath with exercise) or greater * Restrictive lung disease (e.g. pulmonary fibrosis) * Poorly controlled seizure disorder * Poorly controlled hypertension (blood pressure ≥160/110) * History of extreme sedentary lifestyle (e.g. bed bound) * Orthopedic limitations to aerobic exercise * Severe anemia defined as a hemoglobin \< 8 g/dl or hematocrit \<24 % * Participation in another interventional study that influences weight control\* * Enrollment in this trial in a previous pregnancy\* * Intention of the participant or of the care provider for the delivery to be outside the LIFE-Moms Consortium hospital\* * Participant's unwillingness or inability to commit to a 1 year follow-up of herself or her child, including planning to move away\* * Past or current intravenous drug use (visual check for injection marks, recorded methadone use, self-report) * Self-reported HIV infection (confirmed from medical records or baseline test results) * Inability to functionally participate in group sessions and other study requirements on a regular basis during the complete duration of the study, including but not limited to the documented use of the accelerometer for the periods required by the study * Non Spanish speaking * Plan on giving up infant for adoption '\*' Core eligibility criterion for the LIFE-Moms Consortium