The chapter discusses the impact of prenatal stress on fetal development and health, focusing on epigenetic mechanisms, particularly DNA methylation (DNAm). It reviews candidate gene studies and epigenome-wide association studies (EWAS) that have explored the association between prenatal stress and DNAm changes in peripheral tissues. While some findings suggest a link between prenatal stress and DNAm alterations, particularly in genes related to the hypothalamic-pituitary-adrenal (HPA) axis, the evidence is often inconsistent and lacks robust replication. The chapter also highlights the importance of refining the definition and measurement of prenatal stress, considering its timing and the specific stressor, to better understand its biological embedding. Additionally, it emphasizes the need for longitudinal studies to track the long-term effects of prenatal stress on child health outcomes, including neurobehavioral problems and stress reactivity. The chapter concludes by discussing the potential for epigenetic biomarkers to improve understanding of prenatal programming and enhance children's healthcare.The chapter discusses the impact of prenatal stress on fetal development and health, focusing on epigenetic mechanisms, particularly DNA methylation (DNAm). It reviews candidate gene studies and epigenome-wide association studies (EWAS) that have explored the association between prenatal stress and DNAm changes in peripheral tissues. While some findings suggest a link between prenatal stress and DNAm alterations, particularly in genes related to the hypothalamic-pituitary-adrenal (HPA) axis, the evidence is often inconsistent and lacks robust replication. The chapter also highlights the importance of refining the definition and measurement of prenatal stress, considering its timing and the specific stressor, to better understand its biological embedding. Additionally, it emphasizes the need for longitudinal studies to track the long-term effects of prenatal stress on child health outcomes, including neurobehavioral problems and stress reactivity. The chapter concludes by discussing the potential for epigenetic biomarkers to improve understanding of prenatal programming and enhance children's healthcare.