Discussion
weight gain, overweight or obesity
We found no effect of either EXE or MOT during pregnancy on GWG and obstetric and neonatal outcomes in healthy pregnant women compared to CON. Hence, our predefined hypotheses that GWG would be lower in EXE compared to MOT, and in MOT compared to CON were rejected. Overall, the GWG and incidences of obstetric and neonatal outcomes were within the Institute of Medicine’s recommendations for pregnant women with normal weight [It is noteworthy that the interventions did not reduce GWG compared to CON. These findings contrast with several studies showing reduced GWG compared to standard care after prenatal exercise in healthy [However, even if assuming that our interventions would be effective on reducing GWG and improving obstetric and neonatal outcomes had adherence rate and moderate-to-vigorous-intensity physical activity level been higher, the present study might still be underpowered to detect effects on GWG and the investigated obstetric and neonatal outcomes. Despite that we fulfilled the sample size estimated from our sample size calculation for GWG, this calculation might have been based on too optimistic estimates [Another possible explanation of the negative findings on health outcomes in the present study could be that the results might be biased by the Hawthorne effect since it is uncertain to what extent CON interacted with the activity tracker and improved physical activity level as a result hereof. This could challenge detection of possible differences between intervention groups and CON. However, none of the physical activity measures were per se associated with GWG.Regarding health status of our overall study population, the prevalence of overweight or obesity [The GWG data included in this paper do not take the maternal body composition into account. Since exercise-induced improvement of body composition has been shown in both pregnant [A strength of the present study is that the last weight measurement is obtained at delivery enabling us to develop a novel model to estimate GWG for a standardized pregnancy period of 40 + 0 weeks accounting for missing weight measurements and individual differences in GA at delivery. Using this model, we showed a good fit between observed weights and model-predicted weights for all individuals in all three groups, and a complete-case analysis including only participants with weight measurements at delivery showed similar results of GWG as the results of estimated GWG by the model. Thus, this novel method can be used to precisely estimate GWG at specific timepoints throughout pregnancy, for example GWG for the entire pregnancy period. Further, this method allowed us to take GA into account, which can vary up to five weeks within term-deliveries and thus likely influence GWG markedly. Moreover, missing data could be predicted by the model allowing us to report mean GWG at GA 40 + 0 weeks for all 219 study participants even though we only obtained weight data on 131 women at delivery. Thus, this model can be used to standardize measurements of GWG at specific GA timepoints during pregnancy, which can improve comparison of GWG effect sizes between studies. Including self-reported pre-pregnancy weights in the model constitutes a limitation but is justified by the finding that the weight gain slopes are visually comparable between participants in all three groups with no significant outliers.