Exploring early and late pregnancy heart rate variability as incremental predictors of postpartum depression and anxiety symptoms

Early identification of postpartum depression and anxiety is critical for enabling timely preventive interventions. Although antenatal self-report measures are strong and widely used predictors of postpartum mental health outcomes, it remains unclear whether physiological markers such as heart rate variability (HRV) provide incremental predictive value beyond established psychological assessments, particularly when measured at different stages of pregnancy. This study investigated whether HRV indices, measured during early and late pregnancy, before and after a mild cognitive-emotional stressor, contribute incremental predictive information for postpartum depression and anxiety symptoms beyond established psychosocial and health predictors. Ninety-one pregnant women completed psychological assessments and HRV measurements before and after a mild cognitive-emotional stressor in both early and late pregnancy. Postpartum depression and anxiety symptoms were assessed using validated questionnaires. Random Forest models identified several HRV indices - particularly low-frequency/high-frequency ratio and indices reflecting parasympathetic activity- as meaningful predictors of postpartum outcomes, alongside established psychological factors. The models demonstrated high predictive accuracy, and model comparisons indicated that HRV measures provided a modest yet statistically reliable improvement, specifically reflected in reduced mean absolute error for depression and state anxiety. These findings suggest that HRV provides complementary physiological information beyond self-report measures, supporting its potential role in refining postpartum risk prediction - particularly in cases where self-report indicators alone may be ambiguous.