Disparities in obesity-promoting feeding patterns begin in pregnancy and infancy, underscoring the need for early primary prevention in high-risk groups. We sought to determine the impact of a primary care-based child obesity prevention intervention beginning during pregnancy on maternal infant feeding practices, knowledge, and styles at 10 months in low-income Hispanic families. The Starting Early Program (StEP) randomized controlled trial enrolled pregnant women at a third trimester visit. Women ( = 533) were randomized to standard care or an intervention with prenatal/postpartum individual nutrition counseling and nutrition and parenting support groups coordinated with pediatric visits. Feeding practices (breastfeeding, family meals, juice, and cereal in the bottle) were assessed using questions from the Infant Feeding Practices Study II. Feeding styles were assessed using the Infant Feeding Style Questionnaire. We analyzed impacts on feeding practices, knowledge, and styles using regression analyses adjusting for covariates. Four hundred twelve mothers completed 10-month assessments. Intervention mothers were more likely to give breast milk as the only milk source [adjusted odds ratio (AOR) 1.65, 95% confidence interval (CI) 1.06-2.58] and have daily family meals (AOR 1.91, 95% CI 1.19-3.05), and less likely to give juice (AOR 0.60, 95% CI 0.39-0.92) or cereal in the bottle (AOR 0.54, 95% CI 0.30-0.97) compared to controls. Intervention mothers were more likely to exhibit lower pressuring, indulgent and laissez-faire feeding styles, and to have higher knowledge. Attending a greater number of group sessions increased intervention impacts. StEP led to reduced obesity-promoting feeding practices and styles, and increased knowledge and provides great potential for population-scalability.