Maternal stress, physical activity, and body mass index during new mothers' first year postpartum.

We evaluated associations of parenting stress, including depressive symptoms, with 51 first-time mothers' light and moderate physical activity and body mass index during the first year postpartum. The Parenting Stress Index and 24-hour physical activity recalls were completed during the first year postpartum (mean time elapsed since birth: 6 months). Direct relationships between identified variables were tested, and then hierarchical linear regression was used to assess hypothesized relationships among body mass index, physical activity, and parenting stress. Effects of parenting stress on the relationships between postpartum body mass index, light physical activity, and moderate physical activity were evaluated after controlling for factors known to be associated with overweight and low levels of physical activity in women. Mean postpartum body mass index = 27.4 kg/m² ± 7.7, range = 18-50 kg/m². Mean reported hours of light physical activity = 11.2 ± 3.0, and moderate physical activity = 4.5 ± 3.0 per day. Postpartum body mass index was not associated with parenting stress, but was positively related to higher pre-pregnancy body mass index (r = .89, p < .01) and light physical activity (r = .32, p < .05), and was negatively related to moderate physical activity (r = -25, p < .08). Higher postpartum body mass index (β = .27, p < .05), less concern regarding parenting competence (β = -.95, p < .001), and more depressive symptoms (β = .66, p < .01) were associated with more light physical activity (R² = .48, p < .001). More moderate physical activity (R² = .45, p < .001) was associated with lower postpartum body mass index (β = -.27, p < .05), more concern about parenting competence (β = 1.0, p < .001), and less depressive symptoms (β = -.68, p < .01). Higher postpartum body mass index (R² = .89, p < .001) was associated with higher pre-pregnancy body mass index (β = .99, p < .001), more pregnancy weight gain (β = .22, p < .001), less attachment (β = -.68, p < .01), and less social isolation (β = -.13, p < .02). These data suggest that interventions that target parenting stress and depressive symptoms in addition to physical activity are needed to prevent development of overweight in new mothers.