Effect of a prenatal lifestyle intervention on physical activity level in late pregnancy and the first year postpartum

BACKGROUND: Despite documented health benefits for mother and baby, physical activity (PA)-level tends to decline in pregnancy. Overweight/obese and physically inactive women are two selected groups at increased risk of pregnancy complications. Thus, efficient strategies to maintain or increase PA-level in pregnancy and the postpartum period, especially among these women, are warranted. This secondary analysis examined the effect of a prenatal lifestyle-intervention on PA-level in late pregnancy and the first year postpartum, with subanalysis on initially physically active versus inactive and normal-weight versus overweight/obese women. METHOD: The Norwegian Fit for Delivery (NFFD) randomized controlled trial included healthy primiparous women with singleton pregnancies and body mass index (BMI) ≥19 kg/m(2) assigned to an intervention group, n = 303 (twice weekly group-exercises and dietary counseling) or a control group, n = 303 (standard prenatal care). The International Physical Activity Questionnaire short-form was used to assess PA-levels at inclusion (mean gestational week (GW) 16), GW 36, and six and 12 months postpartum. RESULTS: At GW 36, a positive intervention-effect with a significant between-group difference in total PA-level compared to time of inclusion was found for the total group (530 MET-min/week, p = 0.001) and the subgroups of normal-weight (533 MET-min/week, p = 0.003) and initially active women (717 MET-min/week, p<0.001). Intervention-effect was dependent on exercise-adherence among overweight/obese and inactive women. Compared to time of inclusion, the intervention groups maintained total PA-level at GW 36, while total PA-level decreased in the control groups. The PA-levels increased postpartum, but with no significant differences between the randomization groups. CONCLUSION: The NFFD prenatal combined lifestyle intervention had a significant effect on TPA-level in late pregnancy among women entering pregnancy normal-weight or physically active, thereby preventing the downward trend typically seen during pregnancy. Intervention-effect among overweight/obese and physically inactive women was, however, dependent on exercise-adherence. Long-term intervention-effect was not observed in the postpartum period.