Effects of Maternal Heartbeat Exposure on Neonatal Autonomic Regulation

During intrauterine life, the fetus is continuously exposed to rhythmic sensory stimuli; among these, the maternal heartbeat is one of the earliest and most biologically salient, contributing to the early organization of physiological regulation. This exploratory longitudinal observational study examined whether exposure to the maternal heartbeat influences neonatal autonomic activity and whether this response is moderated by prenatal maternal psychological distress.

Sixteen dyads of mother-child were included in the analyses. Pregnant women were first assessed between 24 and 28 weeks of gestation: maternal distress was measured using the Depression Anxiety Stress Scales-21 (DASS-21), and maternal heartbeat recordings were obtained. At 3-4 weeks postpartum, neonates were exposed to recordings of their own mother's heartbeat. Neonatal heart rate variability (HRV) was assessed using electrocardiography at rest and during the hearing of the maternal heartbeat.

Exposure to the heartbeat significantly reduced high-frequency (HF) HRV compared to baseline (p = 0.037), providing evidence for modulation of parasympathetic activity. Importantly, an interaction between condition and maternal distress was observed (p = 0.021), suggesting that neonatal autonomic responses differ as a function of maternal psychological state.

Overall, these preliminary findings suggest that neonatal autonomic responses to maternal heartbeat exposure may not be uniform but may vary according to maternal psychological distress, highlighting the potential role of the maternal psychophysiological context in shaping early autonomic regulation.