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

Abstract

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/m2 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.

Fig 1. Consort diagram showing the flow of participants throughout the study.

Fig 2. Total physical activity level in MET-minutes/week.

IG; intervention group (n = 295). CG; control group (n = 294). Total PA; total physical activity; walk + moderate physical activity + vigorous physical activity. - - - blue = intervention groups and - - - dark grey = control group. ^_______blue = intervention group adherent and ^….blue = intervention group nonadherent. *Statistically significant change in physical activity level compared to time of inclusion (p<0.05). # Statistically significant change in total PA level compared to time of inclusion, between intervention group, intervention adherent/nonadherent subgroups and control group (p<0.05).

Fig 3. Total physical activity level in MET-minutes/week for the inactive and the active participants.

- - - physically inactive and ^_______ physically active, blue = intervention group (IG) and dark grey = control group (CG). *Significant change in physical activity level compared to time of inclusion (p<0.05). #Significant difference in physical activity level between the intervention group and the control group compared to time of inclusion (p<0.05).

Fig 4. Total physical activity level measured between participants in the intervention group adherent and nonadherent to group-exercises and the control group.

1: time of inclusion, 2: gestational week 36, 3: 6 months postpartum, 4: 12 months postpartum. ^_____Blue; intervention adherent. -----Blue; intervention nonadherent. .....Dark grey; control group. A; Inactive; participants physically inactive at time of inclusion (<600 MET-min/week of MVPA). B; Active; participants physically active at time of inclusion (≥600 MET-min/week of MVPA). C; Normal weight; prepregnancy BMI < 25 kg/m². D; Overweight/obese; prepregnancy BMI ≥ 25 kg/m². # Statistically significant change in total physical activity level compared to time of inclusion, between intervention group adherent subgroup and control group (p<0.05).

Fig 5. Total physical activity level in MET-minutes/week for the normal weight and the overweight/obese.

IG; intervention group. CG; control group. NW; normal weight. OW/OB; overweight/obese. - - - normal weight and ^_______ overweight/obese, blue = intervention group (IG) and dark grey = control group (CG). *Significant change in physical activity level compared to time of inclusion (p<0.05). #Significant difference in physical activity level between the intervention group and the control group compared to time of inclusion (p<0.05).