Senior Research Scientist Google San Francisco, CA, United States
Introduction: Regular physical activity during pregnancy is associated with improved pregnancy outcomes such as decreased risk of preterm birth, preeclampsia, and gestational diabetes. This is the largest and most complete data set of step count tracking before, during and after pregnancy using wearables to date. Methods: Wearable (Fitbit) users from 2019-2022 who are greater than 21 years of age and located in the United States or Canada participated in this retrospective, longitudinal, and institutional review board approved study. Only participants who wore a device for at least 80% of the time for greater than 90 days pre-pregnancy, throughout pregnancy, and greater than 90 days post-delivery were included. Results: Of the 13,457 participants who gestated and completed our survey, 3,057 met the inclusion criteria. Overall, there was an average decrease of 2,064 (CI 95% 1992-2136) steps from pre-pregnancy (average 8570 [CI 95% 8463-8677] steps) to delivery (average 6510 [CI 95% 6422-6599] steps). The largest drop in steps occurred between 4 and 9 weeks gestation at 1686 (CI 95% 1600-1772) steps. Steps counts remained fairly stable during the second trimester followed by a steady decline throughout the third trimester. Even at 90-120 days postpartum, the average step count remained below pre-pregnancy levels at 7,770 steps (CI 95% 7671-7869) steps. Conclusion/Implications: Our study is consistent with other studies that showed an overall decrease in step count during pregnancy. Interestingly, the largest reduction in step count occurred before 10 weeks gestation. Furthermore, average step count continued to be below pre-pregnancy levels at 90 to 120 days postpartum.
