Physical activity during pregnancy and perinatal depression risk: A population-based cohort study

Perinatal depression has long-lasting consequences on maternal and infant health. Increased systemic inflammation in pregnancy is a risk factor for perinatal depression. We have previously shown that moderate physical activity during pregnancy reduces systemic inflammation. However, the association between intensity and duration of physical activity in pregnancy and perinatal mental health, and whether inflammation mediates this putative association, have not been previously assessed. In a pre-birth Australian cohort, the Barwon Infant Study, women completed the Edinburgh Postnatal Depression Scale and Perceived Stress Scale at 28 weeks of gestation and 4 weeks postpartum, and reported their previous week's physical activity at 28 weeks of gestation using the International Physical Activity Questionnaire. Women were grouped into low, moderate, and high physical activity categories based on the duration and frequency of walking, as well as moderate and vigorous-intensity activity. Circulating inflammatory markers were measured at 28 weeks of gestation. We assessed the association between physical activity and perinatal mental health measures using regression analyses and then investigated mediation by systemic inflammation using nested counterfactual models. Compared to women undertaking the recommended levels of moderate physical activity during pregnancy (n = 319; 41.9%), women in the low physical activity group (n = 377; 49.5%) had higher antenatal Edinburgh Postnatal Depression Scale scores (β = 1.45 , 95% CI (0.78, 2.12), p < 0.001) and higher perceived stress (β = 2.00, 95% CI (0.88, 3.12), p < 0.001); and women in the high physical activity group (n = 66; 8.7%) had higher antenatal Edinburgh Postnatal Depression Scale scores (β = 1.25, 95% CI (0.13, 2.38), p = 0.03), but not Perceived Stress Scale scores. In univariate models, moderate activity types (walking and total days of activity) were negatively associated with antenatal depression risk and perceived stress. The associations between physical activity during pregnancy and postpartum Edinburgh Postnatal Depression Scale and Perceived Stress Scale scores were less evident. Systemic inflammatory markers did not mediate the associations between physical activity and Edinburgh Postnatal Depression Scale/ Perceived Stress Scale scores. Our findings indicate that moderate levels of physical activity during pregnancy, such as walking, were associated with better concurrently measured antenatal mental health, informing simple and achievable advice that should be incorporated into pregnancy guidelines and clinical practice. Further studies should include serial measures of physical activity, Edinburgh Postnatal Depression Scale and Perceived Stress Scale in pregnancy for a more comprehensive understanding of the causal relationship between physical activity and perinatal mental health.