Background

Women who start pregnancy with a high body mass index (BMI) or experience excessive gestational weight gain (GWG) are at risk for weight retention. Physical activity post childbirth has the potential to limit retention. The purpose of this study was to assess if physical activity was associated with weight at 6 and 12 months postpartum.

Methods

Secondary analysis of postpartum women who participated in a RCT (2009-2014). Linear regression was used to assess relationships between physical activity (Mets/hour/week), measured by the pregnancy physical activity questionnaire (PPAQ) at 6 and 12 months postpartum, and weight change (kg) from early pregnancy to 6 (n = 841) and 12 months (n = 684) postpartum, adjusting for early pregnancy BMI, intervention arm, and GWG. Interactions between BMI, physical activity and GWG were assessed.

Results

Approximately 45% of pregnant women gained excessively. Linear regression models at 6 months were significant: GWG (CI: .403, .522) and excessive GWG (CI: 2.734, 4.285) in separate models were positively associated with weight retention; among women with excessive GWG physical activity was associated with weight retention (CI: .002, .032). At 12 months regression models were significant: GWG (CI: .158, .324), physical activity (CI: .014, .048) and BMI (CI: .042, 1.526) were positively associated with weight retention. There was an interaction between BMI and physical activity (CI; .001, .008) only among women who gained excessive GWG.

Conclusions

Increased physical activity was associated with higher weight retention. The PPAQ may not capture physical activity that alters weight retention. At 6 and 12 months postpartum more physical activity did not decrease weight retention and at 12 months it did not decrease weight when BMI was higher. Measures of physical activity capturing high intensity may be the correct construct to capture to predict postpartum weight retention.