Obesity and diabetes rates continue to rise, and racial and gender disparities persist. 23% of women gain ≥ 20 kg through young adulthood, which is associated with development of diabetes and greater mortality. Because many women experience pregnancy, excessive gestational weight gain (GWG) and post-partum weight retention (PPWR) are potentially modifiable contributors to future obesity and diabetes in both women and their children. The aim of this R-18 Pragmatic Randomized Controlled Trial (RCT) is to test the effectiveness of Healthy for Two / Healthy for You (H42/H4U), an innovative evidence-based pregnancy/postpartum health coaching intervention that is remotely-delivered (phone coaching + web-based platform + mobile phone behavioral tracking), aimed at promoting healthy GWG and postpartum weight loss. We will embed H42/H4U into prenatal care clinics that serve a racially and economically diverse population, leverage existing staff as trained health coaches and community health workers, and test its effectiveness and implementation in a pragmatic RCT. We aim to 1) Compare the effectiveness of the H42/H4U remotely-delivered health coaching intervention integrated into prenatal care compared with Usual Care among 380 pregnant and postpartum women enrolled from 6 prenatal clinics and; 2) Assess organizational factors that impact the implementation of the intervention into prenatal care clinics, including costs of intervention delivery and provider and staff satisfaction to inform future dissemination. The primary outcome will be GWG. Maternal and infant secondary outcomes include excess GWG, GDM incidence, PPWR, infant birth weight and at 4 and 6 months, maternal health behaviors (diet, physical activity, breastfeeding) and maternal wellness (depression, sleep, stress). This study will advance a potentially powerful, prenatal care-based strategy to reduce obesity in childbearing women and thereby the intergenerational effects on their children. Our team brings together academic and community-based obstetricians, a population health program, and researchers with experience in developing, testing and implementing behavioral interventions in both pregnant and non-pregnant adults in real world settings to enable wide dissemination. Ultimately, we aim to reduce obesity, diabetes and other obesity-related complications in mothers and their children, and ensure high quality care delivery that prevents obesity and diabetes through a population health approach to prenatal care.