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.

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.

Aim 1. To assess the efficacy of the adapted HFF program with 275 military families from health centers at military bases in Washington, Florida, and Nevada. Families with an active-duty servicemember parent will be randomized to Healthy Family Foundations (HFF) or control condition. Primary outcomes consist of infant weight status (weight-for-length z-score) and maternal postpartum weight retention through 12 months; fathers' change in weight to 12 months is a secondary outcome.

Aim 2. To test mediation: HFF will foster healthy (A) parent weight outcomes via mutual parental support around healthy lifestyle behaviors (physical activity, nutrition, sleep); and (B) child weight status via coparenting support for health-related parenting (responsive feeding and promotion of sleep, physical activity, stress regulation).

Aim 3. To assess whether baseline parent characteristics (financial stress, mental health, relationship conflict, or weight status) or participant program engagement moderate program effects.

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.

Inclusion Criteria:

• Two-parent military families (one or more parents are active duty military)
• Expecting a first child, through 7 months gestation

Exclusion Criteria:

• Clinical exclusion criteria for parents apply to males and females (active diagnosis of cancer, AIDS, palliative medicine patients, malabsorptive conditions, uncontrolled multiple sclerosis, and severe cognitive impairment), and to females (multiple gestation)
• Families will be excluded if both parents do not participate.