Partnering and parenting transitions in Australian men and women: associations with changes in weight, domain-specific physical activity and sedentary behaviours

Background Partnering and parenting are important life-stage transitions often accompanied by changes in social networks, roles and responsibilities. There have been no longitudinal studies examining associations of partnering and parenting with changes in domain-specific physical activity (PA) and sedentary behaviours, and our understanding of whether these transitions are associated with weight change is limited. Methods Two thousand one hundred and twenty-four Australian adults from a national cohort (mean age 31.7 (2.7) years, 47.5% male) completed questionnaires at baseline (2004-06) and follow-up (2009-11), reporting marital and parental status. Weight (kg) was measured at baseline and self-reported at follow-up. PA and sedentary behaviours (sitting and television (TV) viewing) were self-reported in a subset (n = 1221). Linear regression estimated the longitudinal associations of parenting and partnering transitions with PA, sedentary behaviours and weight at follow-up, adjusted for baseline value of the respective outcome variable, age, education, follow-up duration and other life-stage transition. Results During the 5-year follow-up, 17.3% men and 12.9% women partnered, and 27.3% men and 19.1% women had their first child. Compared to staying not partnered, partnering was associated with an increase in total PA (177.5mins/week, 95% Confidence Interval (CI) 18.0 to 337.0) among men and a greater weight gain (2.2 kg, 95% CI 0.6 to 3.7) among women. Compared to remaining child-free, having a first child was associated with greater reductions in total PA (- 123.9mins/week, 95% CI - 248.8 to 1.1) and TV viewing time (- 27.0mins/day, 95% CI - 50.6 to - 3.3) among men. Women who had their first child had greater weight gain (1.4 kg, 95% CI 0.1 to 2.7) but spent less time sitting (- 103.8mins/day, 95% CI - 135.5 to - 72.1) than those remaining child-free. For women, having additional children was associated with less sitting time (- 39.4mins/week, 95% CI - 66.0 to - 12.8) than having the same number of children. Conclusions Partnering was associated with an increase in men's total PA and women's weight. Transitions into parenthood with a first child or additional children were associated with potentially health-impairing changes in weight and PA, but health-promoting changes in sedentary behaviours. Future PA promotion strategies should pay attention to men who had their first child to mitigate declining total PA.