Maternal mental health conditions significantly contribute to pregnancy-related mortality in the United States. Approximately 20-25% of postnatal women exhibit symptoms of depressive and anxiety disorders. Mental health is influenced by stress, which affects mood, cognition, and behavior. Heart rate variability (HRV), the time interval between consecutive heartbeats, is a physiological marker for assessing stress levels, providing critical insights into the body's autonomic responses. Wearable devices measuring HRV offer a non-invasive method to monitor stress and mental health, enabling early detection of maternal stress dynamics to facilitate timely interventions. In this scoping review, we aimed to capture the current state of science on two areas of focus: (1) utilization of wearable technology for HRV monitoring in pregnant and postpartum women, (2) findings from these perinatal HRV studies, including observed HRV trends throughout pregnancy and postpartum, as well as the association between HRV, perinatal stress, and mental health. The six included perinatal HRV studies employed five fitness tracking wearables, utilizing either periodic or continuous 24-h monitoring. Findings include evidence that HRV declines during pregnancy, with a return to normal levels postpartum. Associations between HRV and stress were inconsistent across studies, with some demonstrating correlations and others reporting no relationship. Postpartum HRV measurements effectively differentiated between women with postpartum depression (PPD) versus those with adjustment disorder (AJD), demonstrating high diagnostic accuracy. In this scoping review, HRV shows promise as a stress biomarker among pregnant/postpartum people, although more work is needed to standardize optimal methods of wearable HRV measurement in this population.
