Long-term effects of participation in a prenatal exercise intervention on body weight, body mass index, and physical activity level: A 6-year follow-up study of a randomized controlled trial

Abstract

Background: Growing evidence supports that physical activity and exercise during pregnancy is favorable for the mother, with persisting benefits in the postpartum period. However, there is scant knowledge of the effect of a prenatal exercise program on long-term health and lifestyle habits. Objectives: This 6-year follow-up study of a randomized controlled trial had two aims: (1) compare body weight, weight retention and body mass index (BMI) in the intervention group and control group, and (2) evaluate effects on physical activity level and recreational exercise. Materials and methods: Out of 105 participants initially randomized to either an intervention group, n = 52 (twice weekly group-exercises and physical activity counselling) or control group, n = 53 (standard prenatal care), 80 women (76.2%) participated in the present long-term follow-up study, performed in a general community in Oslo, Norway. Data were collected through a standardized telephone interview based on the baseline protocol and a modified Physical Activity and Pregnancy Questionnaire (PAPQ). Body weight at 6 years follow-up was self-reported (kg), and calculation of current BMI (kg/m2) was based on self-reported weight and measured height at study inclusion. Investigators were unaware of the original randomization at the time of the interviews. Analyses of covariance were used to examine the difference in change in body weight and BMI between the groups. Even though the MET-values were not normally distributed, differences were examined using a two-sided independent sample t-test due to large sample size (n ≥ 30). Results: At 6 years follow-up there were no differences in mean BMI (kg/m2) (24.0 ± 3.8 versus 24.8 ± 4.0, p = .37), physical activity level (4167 ± 2638 versus 3925 ± 3075 MET-min/week, p = .67) or recreational exercise (630 ± 1290 versus 720 ± 1005 MET-min/week, p = .88) between the intervention and control group, respectively. Subgroup analysis of participants with high adherence during the intervention 6 years ago (≥24 prenatal exercise classes), showed a positive intervention effect at long-term follow up in body weight (kg) (62.8 ± 7.9 versus 70.8 ± 11.8, p = .03) and BMI (kg/m2) (22.5 ± 3.1 versus 24.8 ± 4.0, p = .05), and none (versus 11 in the control group) had gained ≥5 kg compared to prepregnancy weight (p = .02). Conclusions: Women who adhered to the original prenatal exercise intervention demonstrated significantly lower body weight and BMI at 6-year follow-up. Otherwise, no long-term intervention effect was observed.