The Preventive Effect of Physical Activity on Gestational Diabetes Mellitus: A Korean Longitudinal Prospective Cohort Study.

Background: To assess longitudinally physical activity patterns and intensity from pre-pregnancy to postpartum and evaluate the association between timing and type of physical activity and the development of gestational diabetes mellitus (GDM).

Methods: The Korean Pregnancy Outcome Study (KPOS) is a prospective cohort study conducted from 2013 to 2017. Our study included 3,457 participants with singleton pregnancies in KPOS, classified according to the pregnancy outcome: GDM (n=231) and normal (n=3,226). Physical activity data were collected at five time points using the short form of the International Physical Activity Questionnaire: before pregnancy, at 12, 24, and 36 gestational weeks (GW), and 6-8 weeks postpartum. Pre-pregnancy physical activity was collected through recall at 12 GW.

Results: Maternal age, pre-pregnancy body mass index, educational status, smoking, mini dietary assessment index, first-degree family history of diabetes, hypertension, parity, pre-existing GDM, and previous macrosomia showed significant differences between the GDM group and the normal group (P<0.05 for all). Pre-pregnancy muscle-strengthening activity was significantly associated with a lower risk of GDM (adjusted odds ratio, 0.46; 95% confidence interval, 0.25 to 0.85).

Conclusion: These findings suggest that physical activity, such as muscle-strengthening activities before pregnancy, could be a preventive strategy to reduce GDM risk. Although the study does not provide evidence that physical activity during pregnancy and postpartum reduces GDM risk, it offers significant insights into the importance of maintaining a healthy level of physical activity from pre-pregnancy to prevent GDM.