Maternal Moderate-to-Vigorous Physical Activity before and during Pregnancy and Maternal Glucose Tolerance: Does Timing Matter?

Purpose: To assess prospective associations between moderate-to-vigorous physical activity (MVPA) from preconception through pregnancy and glucose metabolism. Methods: The sample consisted of 2388 women from the NICHD Fetal Growth Studies-Singletons, which enrolled US pregnant women between 8 and 13 wk of gestation. Women recalled their MVPA in periconception (past 12 months, inclusive of first trimester), early-to-mid (13-20 wk of gestation), and mid-to-late second trimester (20-29 wk). These data were obtained at study visits that occurred at enrollment (8-13 wk) and at follow-up visits at 16 to 22 wk and 24 to 29 wk. Moderate-to-vigorous physical activity was recalled using the Pregnancy Physical Activity Questionnaire. Glucose challenge test and oral glucose tolerance test results and gestational diabetes diagnosis (defined by the Carpenter-Coustan criteria) were extracted from medical records. ANCOVA and Poisson regression with robust error variance were performed to estimate associations between MVPA and glucose concentrations and gestational diabetes risk, respectively, controlling for age, race/ethnicity, and prepregnancy body mass index. Results: Women achieving higher levels of MVPA (>= 75th percentile; 760.5 MET.min.wk(-1)) in early-to-mid second trimester had lower glucose concentrations (beta = -3.9 mg.dL(-1), 95% CI, -7.4 to -0.5) compared with their least-active counterparts (>= 25th percentile; <= 117.0 MET.min.wk(-1)). Women maintaining recommended levels of MVPA from preconception and first trimester through second trimester (early-to-mid: beta = -3.0 mg.dL(-1); -5.9 to -0.1; mid-tolate: beta = -4.2 mg.dL(-1); -8.4 to -0.1) or maintaining sufficient activity throughout second trimester exhibited lower glucose levels (beta = -5.6 mg.dL(-1); -9.8 to -1.4) compared with their inactive counterparts. No statistically significant associations with gestational diabetes were observed. Conclusions: These findings demonstrate that achieving MVPA of at least 760.0 MET.min.wk(-1) in early-to-mid second trimester or maintaining at least 500MET.min.wk(-1) from preconception through second trimester may be related to improved maternal glucose metabolism in the second trimester.