The goal of this clinical trial is to test whether an adaptation of an evidence-based, couple-based preventive intervention at the transition to parenthood improves reduces obesity risk among infants and parents in military families via improved interparental support and coordination around health lifestyle behaviors and parenting. The main question it aims to answer is whether an adapted, innovative family-focused approach to obesity prevention can reduce rapid infant weight gain, new mothers' postpartum weight retention, and fathers' weight status. Participants randomized to the Healthy Family Foundations (HFF) intervention condition will participate in 10 online group classes (5 prenatal and 5 postnatal). Participants randomized to the control condition will receive standard of care and opportunities for education at their site. Researchers will compare the Healthy Family Foundations (HFF) intervention group with a Standard of Care control group to see if there are differences in weight, coparenting support, parent mental health and parent health behaviors.