Purpose:
Postpartum weight retention (PPWR) increases the risk of overweight and obesity. This study aims to identify risk factors for substantial weight retention (≥ 5 kg) at 1 year postpartum.

Methods:
Data were obtained from N = 747 mothers participating in the KUNO-Kids birth cohort study. The following variables were analyzed: sociodemographic variables, pre-pregnancy body mass index, postpartum weight retention at 6 months, gestational weight gain, parity, breastfeeding, mode of delivery, gestational diabetes mellitus, physical activity, diet, alcohol consumption, smoking, sleep, and depression. Variables that showed an association of p < 0.2 with substantial postpartum weight retention (SPPWR) in univariable logistic regression analyses were included in the multivariable logistic regression analysis. Statistical analyses were performed using IBM SPSS.28.

Results:
One year after delivery, mean PPWR was 1.5 kg (SD 5.2 kg), and 21.6% of the women had SPPWR. The multivariable logistic regression model showed a significant negative association of SPPWR with an intermediate educational status compared to a low educational status (OR = 0.27 [95% CI 0.11–0.69]). In addition, PPWR at 6 months was positively associated with SPPWR (OR = 1.55 [95% CI 1.43–1.69]) at 1 year. None of the other associations reached statistical significance.

Conclusion:
Postpartum weight retention may lead to weight gain. Losing weight in the first few months after delivery may prevent substantial postpartum weight retention. Women of low education may particularly benefit from weight loss support.