Hypothetical Behavior Substitutions During The 24-hour Day And Glucose In Early-mid Pregnancy

Sleep, sedentary behavior (SED), and physical activity have independently been associated with glucose tolerance. Interdependent relationships between these behaviors during the 24-hour day and glucose tolerance during pregnancy remain unclear. PURPOSE: To describe associations of hypothetical behavior substitutions during the 24-hour day with glucose in pregnancy. METHODS: We used data from a prospective cohort among pregnant individuals with pre-pregnancy BMI ≥25 kg/m2 (n = 175). In early pregnancy (mean 13 weeks gestation), 24-hour activity was measured using wrist-worn accelerometers for 7 days. Accelerometer data was categorized into in-bed time (proxy for sleep), SED, light intensity physical activity (LPA), and moderate/vigorous intensity physical activity (MVPA) using Tracy and Hibbing algorithms and normalized to 24 hours. Results from 50-g glucose challenge tests in mid-pregnancy (mean 26 weeks gestation) were abstracted from electronic health records. We used compositional isotemporal substitution models to estimate associations between hypothetical reallocations of time (5 to 60 minutes) from one behavior to another and glucose. RESULTS: Mean early pregnancy 24-hour activity composition consisted of 35.0% sleep, 48.2% SED, 14.1% LPA, and 2.7% MVPA. Reallocating 5 to 60 minutes of SED to sleep from the mean 24-hour activity composition was associated with 0.13 mg/dL (95% CI: -0.23, -0.02) to 1.5 mg/dL (95% CI: -2.7, -0.27) lower glucose (Figure). Conversely, reallocating 5 to 60 minutes of sleep to SED was associated with 0.12 mg/dL (95% CI: 0.02, 0.23) to 1.6 mg/dL (95% CI: 0.30, 2.9) higher glucose. Associations for all other behavior substitutions were not statistically significant. CONCLUSION: In individuals with pre-pregnancy overweight or obesity, replacing up to one hour of SED with sleep in early pregnancy may be associated with lower glucose in mid-pregnancy. Supported by: NICHD R00HD100585