Maternal Circadian Preference is Associated With Cardiorespiratory Fitness and Participation in Structured Prenatal...

Circadian preference is associated with physical activity and cardiorespiratory fitness in nonpregnant populations, but little is known about these associations during pregnancy. This study examined whether maternal circadian preference was associated with cardiorespiratory fitness, compliance with a structured prenatal exercise intervention, and longitudinal changes in maternal lipid concentrations.

Pregnant women participating in two randomized controlled trials of prenatal exercise self-classified as Morning, More Morning, More Evening, or Evening chronotypes. Associations between chronotype and cardiorespiratory fitness (VO₂peak), exercise compliance, and longitudinal lipid adaptations during pregnancy were examined using appropriate multivariable statistical models.

Greater Evening preference was associated with lower VO₂peak after adjustment for age, BMI, and MVPA (B = -1.40 mL·kg^-1·min^-1, standardized β = -0.25, p = 0.005). Exercise compliance differed across chronotype groups (p < 0.001; partial η² = 0.185), with significantly lower compliance among Evening chronotypes than each of the other groups (all p < 0.001). In exploratory longitudinal analyses, a significant Time × Chronotype interaction was observed for HDL cholesterol (p = 0.009). HDL cholesterol increased from 16 to 36 weeks' gestation among Morning-oriented women but did not significantly change among evening-oriented women.

Maternal circadian preference was associated with cardiorespiratory fitness and participation in a structured prenatal exercise program. The substantially lower session attendance among Evening chronotypes suggests that circadian preference may be a useful characteristic for understanding individual differences in participation in prenatal exercise. Exploratory findings regarding HDL trajectories warrant confirmation in larger longitudinal studies.