Maternal psychological stress during pregnancy can lead to neurological disorders in offspring, such as anxiety, depression, attention-deficit/hyperactivity disorder, and autism, as well as child’s immune system alteration and preterm birth. This chapter reviews current evidence on how maternal psychological stress crosses the placenta and reaches the fetus. Maternal stress activates multiple placental pathways that influence fetal development, negatively impacting its prenatal and postnatal development. This occurs primarily through activation of the hypothalamic-pituitary-adrenal axis, alteration of placental blood flow, release of proinflammatory cytokines, and oxidative stress, with cortisol as the main mediator. Alteration of the mother gut microbiota composition, catecholamines, serotonin, and tryptophan production compromised fetal microbiome, immune system, and neurodevelopment. The chapter advocates integrative preventive strategies—psychosocial support, antioxidant-rich nutrition, and nutritional interventions—to mitigate maternal stress and safeguard long-term offspring health.