HealthyMoms : a smartphone application to promote healthy weight gain, diet and physical activity during pregnancy : a randomized controlled trial

Sammanfattning: Background: The prevalence of overweight and obesity is a major public health concern, also among pregnant women. Alarmingly, around half of pregnant women in high income countries exceed the recommendations for an optimal gestational weight gain (GWG). Clearly, scalable interventions are needed, and digital interventions have the potential to reach many women and promote healthy GWG. In addition to intervention effectiveness, it is also important to investigate user engagement and satisfaction with the intervention as well as potential intervention effects on the infant (e.g., infant growth and body composition). Finally, although it is clear that lifestyle factors such as low levels of physical activity may contribute to excessive GWG, levels of physical activity tend to decrease during pregnancy. However, current knowledge on how time spent in different physical activity intensities as well as sedentary behavior and sleep (i.e., movement behaviors) in pregnancy is scarce. Thus, to further understand the impact of physical activity during pregnancy and improve future interventions and guidelines research on this topic is needed. Aims: The overall and primary aim of this thesis was to investigate the effectiveness and usability of a 6-month digital lifestyle intervention (the HealthyMoms app) intended to promote a healthy weight gain, diet, and physical activity during pregnancy. Furthermore, as a secondary aim, I explored how time spent on different movement behaviors (i.e., sleep, sedentary behavior, light physical activity [LPA], and moderate-to-vigorous physical activity [MVPA]) changed from early to late pregnancy, and how such changes were associated with maternal weight and body composition (i.e., fat- and fat free mass) as well as cardiometabolic health indicators. This may be important for future development of the HealthyMoms app as well as for other researchers when developing lifestyle interventions in this field. The specific aims of the included papers were: Paper I: To investigate the effectiveness of the HealthyMoms app on i) GWG (primary outcome), and ii) body fatness, dietary habits, MVPA, glycemia, and insulin resistance (secondary outcomes) in comparison to standard maternity care. Paper II: To explore participants’ engagement and satisfaction with the 6-month usage of the HealthyMoms app. Paper III: To investigate i) the effects of the HealthyMoms app on infant body composition 1-2 weeks postpartum, and ii) whether a potential intervention effect on infant body composition is mediated through maternal GWG. Paper IV: To examine cross-sectional and longitudinal associations of 24-hour movement behaviors (i.e., sleep, sedentary behavior, LPA, and MVPA) with GWG, maternal body composition and cardiometabolic health in i) early- (gestational week 14), and ii) late pregnancy (gestational week 37). Methods: Paper I: A 2-arm parallel randomized controlled trial including 305 pregnant women. Women were randomized in a 1:1 ratio to either the intervention (n=152) or control group (n=153) upon completion of baseline measures in gestational week 14. The control group received standard care while the intervention group also received the HealthyMoms app for six months. Outcome measures were assessed at baseline and follow up in gestational week 37. The primary outcome was GWG, and secondary outcomes included body fatness (air- displacement plethysmography using Bod Pod), dietary habits (Swedish Healthy Eating Index) and MVPA (ActiGraph wGT3x-BT accelerometer), glycemia and insulin resistance. Linear regression was used to examine differences in primary and secondary outcomes between the intervention and control group. Paper II: A qualitative study including 19 women from the intervention group in the HealthyMoms trial. Semi-structured exit interviews were performed. The interviews were audio-recorded and fully transcribed, coded and analyzed using thematic analysis with an inductive approach. Paper III: A secondary outcome analysis including 305 healthy full-term infants from the HealthyMoms trial. Body composition was measured using air-displacement plethysmography (Pea Pod) at 1-2 weeks of age. Linear regression was used to examine the effect of intervention allocation (intervention vs control) on infant outcomes. Paper IV: An observational study utilizing both cross-sectional (n=273) and longitudinal data (n=242) from the HealthyMoms trial. Exposure (movement behaviors [ActiGraph wGT3x- BT accelerometer]) and outcome measures (body composition [Bod Pod] and cardiometabolic health [metabolic syndrome score, MetS score; homeostatic model assessment for insulin resistance, HOMA-IR]) were assessed in gestational weeks 14 and 37. To investigate associations between different combinations of movement behaviors with body composition and cardiometabolic health compositional data analysis was used. Results: Paper I: Overall, no statistically significant effect on GWG (P=0.62) was found; however, the results from both the imputed and completers-only analyses indicate that women in the intervention group with a pre-pregnancy BMI ≥25 kg/m2 gained less weight compared to their counterparts in the control group (-1.33 kg; 95% CI -2.92 to 0.26; P=0.10, and -1.67 kg; 95% CI -3.26 to -0.09; P=0.031, respectively). Among women with overweight and obesity Bayesian analyses showed that there was a 99% probability of any intervention effect on GWG, and an 81% probability that this effect was over 1 kg. The intervention group had higher scores for the Swedish Healthy Eating Index at follow up than the control group (0.27; 95% CI 0.05-0.50; P=0.02). No statistically significant differences in the other outcomes (i.e., body fatness, MVPA, glycemia, and insulin resistance) between the intervention and control groups at follow up were observed (P≥0.21). Paper II: One main theme (‘One could suit many – a multi-functional tool to strengthen women’s health during pregnancy’) and two subthemes (‘Factors within and beyond the app influence app engagement’ and ‘Trust, knowledge, and awareness – aspects that can motivate healthy habits’) were revealed from the thematic analysis. These illustrated that a health and pregnancy app that is easy to use, trustworthy and appreciated can inspire a healthy lifestyle during pregnancy. Factors within the app (e.g., regular updates and feedback) were perceived to motivate both healthy habits and app engagement, while factors beyond the app were described to both motivate (e.g., interest, motivation, and curiosity) and limit (e.g., pregnancy-related complications, lack of time) app engagement (first subtheme). Aspects such as high trustworthiness of the app, increased knowledge, and awareness from using the app were described as important and motivated participants to improve or maintain healthy habits during pregnancy (second subtheme). Paper III: No statistically significant effect on infant weight (β=-0.004, P=0.94), length (β=- 0.19, P=0.46), body fat percentage (β=0.17, P=0.72) or any of the other body composition variables in the multiple regression models (all P ≥ 0.27) were observed at 1.8 (SD 0.4) weeks of age. Moreover, no mediation effect through GWG on infant outcomes were found. Paper IV: Reallocating time to MVPA in favor of the other behaviors was associated with lower MetS score (all γ≤0.343, all P≤0.002), while higher levels of LPA were associated with lower body weight (adj. γ=-5.959, P=0.047) and HOMA-IR (all γ≤-0.495, P≤0.047) in early pregnancy. Increasing LPA relative to the other behaviors in early pregnancy was associated with lower fat mass index (adj.: γ=-0.668, P=0.028), glucose levels (all γ≤-0.219, all P≤0.043), HOMA-IR (all γ≤-0.619, all P≤0.016) and MetS score (all γ≤-0.410, all P≤0.040) in late pregnancy. Conclusions: The results from this thesis demonstrate that a digital lifestyle intervention (the HealthyMoms app) has potential to promote healthy dietary habits in women representing all BMI-categories and decrease weight gain during pregnancy in women with overweight and obesity without compromising offspring growth. Moreover, the HealthyMoms app was appreciated and used to a high extent which further shows its potential to be implemented in healthcare to promote a healthy lifestyle during pregnancy. Furthermore, the results indicate that LPA might be a stimulus of enough intensity to improve body composition and cardiometabolic health indicators and could be a key focus in future health promotion initiatives during pregnancy.