The role of change in peripartum heart rate variability in the prediction of depressive symptoms 18 months after childbirth: a follow-up study

Low vagally-mediated HRV (vmHRV) during peripartum predicts higher depressive symptoms (DS). No previous studies have investigated whether vmHRV recovery following delivery increases women's vulnerability to postpartum depressive symptomatology. The present study longitudinally explores the interaction between DS during pregnancy and changes in vagally-mediated HRV from pregnancy to 1-month postpartum as predictors of 18-month postpartum depressive symptoms. Nineteen women were evaluated during pregnancy (T1), and 1-month (T2) and 18-month (T3) postpartum. Sociodemographic information, depressive symptomatology (i.e., Edinburgh Postnatal Depression Scale), and a time-domain HRV index (i.e., the root mean square of successive difference between NN intervals, rMSSD) measured through a smartphone application were evaluated. rMSSD changes between 1-month postpartum and prepartum values were computed. Regression-based moderation analyses were conducted, adjusting for relevant sociodemographic and obstetric covariates. Higher prepartum depressive symptoms were associated with higher depressive symptoms at 18 months postpartum (b = 0.58, SE = 0.15, p < 0.001). Greater vmHRV recovery showed a trend-level inverse association with long-term depressive symptoms (b = −2.19, SE = 1.11, p = 0.053). Importantly, vmHRV recovery significantly moderated the longitudinal association between antenatal and postpartum depressive symptoms (b = −0.41, SE = 0.20, p = 0.039). Johnson–Neyman analyses indicated that the antenatal–postpartum association progressively weakened as vmHRV recovery increased and became non-significant only at high levels of recovery (Δ ln rMSSD >0.61; approximately the upper 10% of the observed distribution). Study limitation include potential artefacts in the physiological signal (e.g., due to hand movements). Women experiencing lower adaptive restoration of parasympathetic activity following childbirth may be at risk of persistent or exacerbated long-term depressive symptomatology. Findings raise the potential for improved identification of at-risk women and exploration of preventive interventions (e.g., HRV-biofeedback, vagus nerve stimulation) to facilitate the recovery of vmHRV and, consequently, mitigate postpartum depressive symptoms.