A coparenting-focused intervention and new mothers’ postpartum obesity risk: Focusing on body mass index during the transition to parenthood

Background: While postpartum is a key life-stage contributing to increased obesity risk for women, existing weight management interventions don’t consider the role of a women’s partner in reducing stress and supporting lifestyle change. Objectives: 1) To assess the effect of an intervention enhancing coparenting relationship quality on maternal body mass index (BMI) from preconception to 12-months postpartum and 2) if intervention status moderated the association of change in cortisol with change in BMI. Subjects/Methods: A randomized controlled trial assessing enhancing coparenting relationships in couples during pregnancy and postpartum (n=57) compared to standard care (n=53) from 2003-6. Heterosexual couples (n=110) were recruited during pregnancy expecting their first child, ≥18 years old and living together. The intervention was Family Foundations, consisting of 8 classes for couples at transition to parenthood focused on enhancing coparenting (4 during and 4 following pregnancy).Results: The main outcome measure was change in maternal BMI and change in cortisol.There was less increase in BMI for mothers in the intervention compared to the control group (-1.03±0.42 kg/m2, p=0.015). There was an interaction between intervention status and cortisol change predicting BMI change (p=0.026) such that cortisol change significantly predicted BMI change among mothers in the control group (p=0.049) but not the intervention group (p=0.204). Conclusion: A coparenting intervention improved maternal postpartum BMI with this effect potentially related to interventions ameliorating the negative effect of stress, as measured by cortisol, on BMI. The role of enhanced coparenting in improving maternal anthropometry and reduced future obesity risk in women warrants urgent attention.