Advanced maternal age, overweight and obese positively correlate to the abnormal plasma glucose among gestational diabetes mellitus women even with physical exercise > 90 min/day: a prospective cohort study in Shanghai.

Physical exercise is an effective intervention in controlling gestational plasma glucose (PG) and reducing adverse pregnancy outcomes. However, evidence regarding the appropriate levels of physical exercise for gestational diabetes mellitus (GDM) women is still limited, especially in China. This study aims to explore the association between physical exercise time and the abnormal plasma glucose (APG) during third trimester, and to develop physical exercise instruction for GDM women with different characteristics. In this study, GDM was diagnosed by 75 g oral glucose tolerance test (OGTT). During the routine antenatal checkups subsequent to GDM confirmation, APG was defined as fasting plasma glucose ≥ 5.10 mmol/L, or 2-h plasma glucose ≥ 8.5 mmol/L with breakfast consumption. Information regarding prenatal examination and birth records among GDM women was extracted from the health information system, and physical exercise data was collected through face-to-face interviews. Group-based trajectory modeling (GBTM) was implemented through R software to identify distinct trajectories of APG percentage, and the restricted cubic spline (RCS) curves with four knots were used to model the dose-response relationship between physical exercise time and the APG percentage among GDM women, in the total and different subgroups. In this study, a P-value less than 0.05 (two-tailed) was viewed as statistical significance. The age of 1448 GDM women ranged from 18 to 45 years, with an average age of 31.22 years. GDM women was divided into low APG group (n = 974, 67.27%) and high APG group (n = 474, 32.73%) based on the GBTM. Logistic regression indicated that GDM women with advanced maternal age (odds ratio (OR) = 2.37 and 95% confidence interval [CI] 1.44-3.90 for those aged 36-45 years, and OR = 1.62 (95% CI 1.02-2.56) for those aged 31-35 years), overweight and obese (OR = 1.70, 95%CI 1.34-2.16) had higher APG risk. The RCS curve indicated that physical exercise could lower the APG percentage among GDM women. However, GDM women with advanced maternal age, overweight and obese still had high APG percentage even when physical exercise exceeded 90 min/day. Physical exercise over 60 min/day could effectively lower the APG risk among GDM women, but even over 90 min/day is less efficient for those with advanced maternal age, overweight and obese, so physical exercise incorporated with other intervention measures should be considered.