Perent walking a baby through a field

FitMum: Validity of tracker on physical activity and sleep, physical activity effect on sleep and one year of physical activity level after birth.

Physical Activity (PA) is a fundamental component of pregnant women health; it has an essential role in preventing serious health conditions such as high blood pressure, gestational diabetes, and obesity. This PhD project will investigate 1) the validity of commercial PA tracker by comparing their data with doubly labelled water (DLW) and pregnancy physical activity questionnaire PPAQ. 2) Will examine the Effects of FitMum PA intervention on sleep quantity and quality as determined by activity trackers. 3) Effects of FitMum RCT on PA level of mothers in one year after delivery.


Danish women showed a low level of PA during their pregnancy, nearly 33% of them engage in PA in early pregnancy and this percentage decrease in the late gestational period (1). Measuring PA among pregnant women is very important to fill the gaps in the area of clinical recommendations, community initiatives and national health policies. Novel technologies, such as wearable devices considered a convenient, safe and cheap method to track PA (2). Although the validity of PA trackers is still under investigation, it might have an advantage in measuring intensity, duration and frequency compared with the valid "gold standard" method such as Doubled Labelled Water DLW (3) or a reliable tool such as Pregnancy PA Questionnaire (PPAQ) (4). A combination of all of these three methods will give a better understanding of the many aspects of PA in pregnant women and ensure accuracy (3)(4). 

On the other hand, sleep disorders may induce dangerous health conditions such as insomnia, diabetes, and obesity. Sleep disorder breathing during pregnancy is considered to affect the mother and fetus health (5). Alteration in sleep pattern among pregnant women is reported to be high (66 % to 94%) (6). There are different medical interventions available to manage sleep disorders. For example, reduce body weight, pharmacotherapy, behavior therapy, and PA. PA showed a positive effect on sleep duration and quality (7)(8) when compared to inactive pregnant women (9). This project will examine the intensity, duration, and frequency of PA recommendations for pregnant women to improve their sleep metrics. Also, it will test the validity of the tracker against another valid method, such as Pittsburgh Sleep Quality Index (PSQI), which is considered a valid and reliable tool to assess sleep metrics among pregnant women (10). Also, polysomnography (PSG) is known as the "gold standard" to validate data from commercial trackers (11-14), and both PSQI and PSG may be used to validate commercial activity trackers in this project. 

Few studies have looked at the effect of exercise after pregnancy, and some find a positive relationship between exercises maintains and reduce weight from early pregnancy to one year after birth (15), and improve psychological outcome in postpartum women after six weeks from birth (16). There is urgent need to see the effect of PA in pregnant women after birth, especially for long-term follow-up after randomized controlled trial (17). This project aims to measure the level of PA from the activity trackers after one year of delivery in FitMum RCT participants.

Project objectives

This PhD project is nested in the FitMum Study and will evaluate the effects of two different exercise programs on physical activity level during pregnancy and on clinical and metabolic health parameters in mother and child. This project will determine the accuracy of PA trackers in comparison with DLW and PPAQ. It will provide insights on the validity of commercial activity trackers as a new approach to increase and measure PA, and their applicability in clinical settings. Moreover, the project will increase our knowledge about the effect of PA on sleep among pregnant women. The result from this project may help to set the recommendations of the PA duration, frequency, and intensity that will positively provide sleep benefits among pregnant women. Consequently, accurate measurements of sleep metrics and valid tools will help clinical research and health agencies to provide beneficial sleep recommendations for pregnant women. Lastly; the study will determine the PA level after three arm RCT, and it will allow us to evaluate the impact of the interventions of PA in pregnant and their adherence to the tracker for future considerations and recommendations. 

FitMum is carried out in collaboration between the University of Copenhagen, Nordsjællands Hospital, Technical University of Denmark, Aarhus University and international researchers. The research project will fill the massive gap in evidence and practice on how to implement physical activity in pregnant women’s everyday life and provide the public sector with evidence of the effect of physical activity programs that can be made available to all pregnant women, independent of the social determinants of health.



  1. Juhl, M., Andersen, P. K., Olsen, J., Madsen, M., Jørgensen, T., Nøhr, E. A., & Andersen, A. M. N. (2008). Physical exercise during pregnancy and the risk of preterm birth: a study within the Danish National Birth Cohort. American journal of epidemiology, 167(7), 859-866.
  2. Harrison, C. L., Thompson, R. G., Teede, H. J., & Lombard, C. B. (2011). Measuring physical activity during pregnancy. International Journal of Behavioral Nutrition and Physical Activity, 8(1), 19.
  3. Plasqui, G., & Westerterp, K. R. (2007). Physical activity assessment with accelerometers: an evaluation against doubly labeled water. Obesity, 15(10), 2371-2379.‏
  4. Santini De Oliveira C, Dos Santos Imakawa T, Christine Dantas Moises E. Physical Activity during Pregnancy: Recommendations and Assessment Tools. Rev Bras Ginecol Obs. 2017;39:424–32.
  5. Punjabi, N. M., Shahar, E., Redline, S., Gottlieb, D. J., Givelber, R., & Resnick, H. E. (2004). Sleep-disordered breathing, glucose intolerance, and insulin resistance: the Sleep Heart Health Study. American journal of epidemiology, 160(6), 521-530.‏
  6. Santiago, J. R., Nolledo, M. S., Kinzler, W., & Santiago, T. V. (2001). Sleep and sleep disorders in pregnancy. Annals of Internal Medicine, 134(5), 396-408.‏
  7. Kredlow, M. A., Capozzoli, M. C., Hearon, B. A., Calkins, A. W., & Otto, M. W. (2015). The effects of physical activity on sleep: a meta-analytic review. Journal of behavioral medicine, 38(3), 427-449.
  8. Driver, H. S., & Taylor, S. R. (2000). Exercise and sleep. Sleep medicine reviews, 4(4), 387-402.‏
  9. Kjeldsen, J. S., Rosenkilde, M., Nielsen, S. W., Reichkendler, M., Auerbach, P., Ploug, T., ... & Chaput, J. P. (2012). Effect of different doses of exercise on sleep duration, sleep efficiency and sleep quality in sedentary, overweight men.‏
  10. Evenson, K. R., Goto, M. M., & Furberg, R. D. (2015). Systematic review of the validity and reliability of consumer-wearable activity trackers. International Journal of Behavioral Nutrition and Physical Activity, 12(1), 159.
  11. Qiu, C., Gelaye, B., Zhong, Q. Y., Enquobahrie, D. A., Frederick, I. O., & Williams, M. A. (2016). Construct validity and factor structure of the Pittsburgh Sleep Quality Index among pregnant women in a Pacific-Northwest cohort. Sleep and Breathing, 20(1), 293-301.‏
  12. Dickinson, D. L., Cazier, J., & Cech, T. (2016). A practical validation study of a commercial accelerometer using good and poor sleepers. Health psychology open, 3(2), 2055102916679012.‏
  13. Kang, S. G., Kang, J. M., Ko, K. P., Park, S. C., Mariani, S., & Weng, J. (2017). Validity of a commercial wearable sleep tracker in adult insomnia disorder patients and good sleepers. Journal of psychosomatic research, 97, 38-44.‏
  14. Mantua, J., Gravel, N., & Spencer, R. (2016). Reliability of sleep measures from four personal health monitoring devices compared to research-based actigraphy and polysomnography. Sensors, 16(5), 646.‏
  15. Olson, C. M., Strawderman, M. S., Hinton, P. S., & Pearson, T. A. (2003). Gestational weight gain and postpartum behaviors associated with weight change from early pregnancy to 1 y postpartum. International journal of obesity, 27(1), 117.‏
  16. Sampselle, C. M., Seng, J., Yeo, S., Killion, C., & Oakley, D. (1999). Physical activity and postpartum well-being. Journal of obstetric, gynecologic & neonatal nursing, 28(1), 41-49.‏
  17. Albright, C. L., Maddock, J. E., & Nigg, C. R. (2009). Increasing physical activity in postpartum multiethnic women in Hawaii: results from a pilot study. BMC Women's Health, 9(1), 4.‏



Bente Merete Stallknecht
Prorector, Professor
Department of Biomedical Sciences
+45 35 32 75 40
10 DECEMBER 2023