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.

Keywords:

• BMI
• body weight
• exercise
• physical activity
• pregnancy
• RCT

Acknowledgments

We thank professor in biostatistics, Ingar Holme, Norwegian School of Sport Sciences for important guidance with the statistical analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Dataset may be available, please contact corresponding author.

Additional information

Funding

The Pregnancy Exercise Intervention was supported by one Ph.D. position at the Norwegian School of Sport Sciences, Department of Sport Medicine, including the use of their exercise facilities free of charge.