Evidence for a Complex Relationship Among Weight Retention, Cortisol and Breastfeeding in Postpartum Women.

Objective To assess the relationship between cortisol slope, a biologic marker of stress, and postpartum weight retention. Methods We included 696 women in a secondary analysis from a multi-site study conducted using principles of community-based participatory research to study multi-level sources of stress on pregnancy outcomes. As a stress marker, we included salivary cortisol slope; the rate of cortisol decline across the day. Pre-pregnancy weight and demographic data were obtained from the medical records. At 6 months postpartum, patients were weighed and returned saliva samples. We built stepwise regression models to assess the effect of demographic variables, cortisol slope and cortisol covariates (wake time, tobacco use and breastfeeding) on postpartum weight retention. Results 45.5 % of participants were African American, 29.2 % White, and 25.3 % Hispanic. Of the Hispanic women 62.5 % were Spanish speaking and 37.5 % were English speaking. In general, participants were young, multiparous, and overweight. Postpartum, almost half (47.6 %) of women studied retained >10 lbs. In multivariable analysis including age, pre-pregnancy BMI and public insurance, cortisol slope was significantly associated with weight retention (β = -1.90, 95 % CI = 0.22-3.58). However, when the model was adjusted for the cortisol covariates, breastfeeding (β = -0.63, 95 % CI = -1.01 to -0.24) and public insurance (β = 0.62, 95 % CI = 0.20-1.04) were the two strongest correlates of weight retention. Conclusions for Practice The association between cortisol slope and postpartum weight retention appears to be influenced breastfeeding status.