Excessive weight that is retained after giving birth tends to be deposited in central rather than peripheral sites. Reported postpartum weight retention averages 0.5–1 kg at 12 months, but as many as one-fourth of women reportedly retain 5 kg or more of weight gained during pregnancy at 6–12 months postpartum. Weight gain during pregnancy is the strongest predictor of postpregnancy weight retention. This prospective cohort study of 902 women sought associations between postpartum television viewing, walking, and trans fat intake on the one hand and, on the other, weight retention of 5 kg or more 12 months postpartum. Data collected in the years 1999–2003 were analyzed in 2005–2006. At 6 months postpartum, participants reported hours per week of TV viewing and the time and intensity of physical activity, and also completed a food frequency questionnaire.
Weight retention 12 months postpartum averaged 0.6 kg in this study, with 12% of mothers retaining 5 kg or more. These women were heavier before pregnancy and were more likely than those who retained less than 5 kg to be nonwhite, unmarried, and primiparous. They also had relatively low incomes and were likelier to have gained excessive weight while pregnant. Based on unadjusted findings, postpartum walking, more vigorous activity, time to return to work, breast feeding, and depression could not be related to high weight retention. On multivariate logistic regression analysis, adjusting for numerous possible confounding factors including maternal sociodemographics, parity, prepregnancy body mass index, gestational weight gain, breast feeding, and smoking status, the odds ratio (OR) of retaining 5 kg or more was 1.24 (95% confidence interval [CI], 1.06–1.46) per daily hour of TV viewing. The OR was 0.66 (95% CI, 0.46–0.94) per daily hour of walking and 1.33 (95% CI, 1.09–1.62) for every 0.5% increment in daily energy intake from trans fat. For women who watched less than 2 hours of TV a day, walked for at least 30 minutes, and consumed less than the median amount of trans fat, the OR for retaining 5 kg of more of gestational weight gain was 0.23 (95% CI, 0.08–0.66).