Transgenerational effects of violence in adolescents exposed to grandmaternal intimate partner violence during pregnancy: Heart rate variability and DNA methylation.

Exposure to intimate partner violence (IPV) during pregnancy may exert enduring effects on physiological stress responses across generations. Although the biological mechanisms remain unclear, epigenetic modifications might be involved. The present study investigated whether heart rate variability (HRV) in adolescence is associated with grandmaternal IPV exposure during pregnancy and DNA methylation (DNAm) patterns. A cohort of 86 participants (57 % female) from São Gonçalo/RJ, Brazil, was assessed at two time points (M ages: 13.7, 18.6 years). At the first assessment, grandmaternal retrospective reports of IPV during pregnancy were collected, and children's DNAm was quantified from saliva samples using Infinium HumanMethylation450 BeadChip. At the second assessment, HRV was recorded while participants completed a control task (sociodemographic interview) and during the recall of their most traumatic lifetime experience (via the UCLA trauma interview). HRV reactivity was computed as the log-ratio between HRV during the trauma and control conditions. Adolescents exposed to grandmaternal IPV during pregnancy showed significantly lower HRV under control condition and increased HRV reactivity compared to non-exposed participants. DNAm at candidate genes (CORIN, BARX1, and CLPX) were associated with HRV metrics. Additionally, over 700 differentially methylated regions were identified in association with HRV. These findings suggest a transgenerational effect of prenatal IPV exposure on adolescent physiological responses, with multiple differentially methylated CpG sites and regions linked to HRV. The results emphasize the urgency of public health efforts to prevent IPV during pregnancy, not only to protect maternal health but also to promote long-term well-being in future generations.