Relationships Between Body Composition and Mental Health During Pregnancy Are Moderated by Physical Activity and Diet

Objective: This study examined the relationships between body fat mass percentage and mental health (depression and anxiety symptoms) during pregnancy, while assessing the moderating effects of physical activity and diet quality. Methods: A prospective cohort of 219 pregnant women was recruited for a longitudinal study of maternal health during pregnancy and offspring outcomes. Pregnant participants were assessed at ∼12 and ∼36 weeks of pregnancy. Body composition was measured using air displacement plethysmography, physical activity was measured with ActiGraph wearables, and diet was measured using the National Institute of Health Diet History Questionnaire-III. Depression and anxiety symptoms were also evaluated using the Beck Depression Inventory-II and State-Trait Anxiety Inventory, respectively, at each study visits. Multivariable mixed linear models adjusted for demographic and socioeconomic factors were used to analyze relationships among these parameters. The study period is from October 2019 to August 2024. Results: Higher body fat mass percentage was significantly associated with increased depression (β= 0.246, P=.014) and anxiety scores (β= 0.241, P=.002). Physical activity moderated the effect of body fat on depression (interaction β=-0.001, P=.017), while diet quality moderated the effect of body fat on anxiety (interaction β=-0.002, P=.047). Conclusion: Higher body fat mass during pregnancy is associated with more symptoms of depression and anxiety. However, increased physical activity and adherence to high-quality diets can attenuate these effects, indicating that lifestyle interventions during pregnancy may improve mental health of pregnant women, particularly for those with obesity.