Genetic Determinants of Stress Reactivity in Pregnancy: A Systematic Review and Meta-Analysis: Implications for Maternal and Fetal Health

Background: Gestation is a period of significant biological plasticity where the intrauterine environment influences fetal development via “fetal programming”. This study systematically reviews and meta-analyzes the association between genetic determinants—specifically the NR3C1, FKBP5, and CRHR1 genes, chosen for their pivotal role in the functional regulation and feedback sensitivity of the hypothalamic–pituitary–adrenal (HPA) axis—and stress reactivity during pregnancy. Methods: Following PRISMA guidelines, a systematic search was conducted across PubMed, Scopus, and Web of Science, yielding an initial total of 1430 records. After removing duplicates and screening 669 studies, a total of 34 primary observational studies were included in the systematic review and qualitative synthesis. For the quantitative synthesis, 27 articles provided sufficient data, resulting in k = 39 independent effect sizes analyzed via a mixed-effects model to account for tissue-specific and cohort-specific outcomes. Results: Systematic analysis reveals that maternal psychosocial stress significantly correlates with NR3C1 hypermethylation, acting as a biological mediator for neonatal cortisol dysregulation and hippocampal volume reduction. The FKBP5 rs1360780 polymorphism emerged as a key moderator of structural vulnerability, showing a “double-hit” effect when combined with epigenetic alterations. Furthermore, the study identifies sex-specific susceptibility, with divergent placental trajectories for male and female fetuses. Meta-analytic estimates confirmed the robustness of these associations (Rosenthal Fail-Safe N = 431,000), despite a general trend toward statistical significance (p = 0.079) in heterogeneous cohorts. Conclusions: The findings underscore a stable link between genetic determinants and prenatal stress reactivity. The interaction between molecular predisposition and environmental factors defines the health of the mother–infant dyad. These results advocate for a transition toward Precision Prenatal Medicine, integrating polygenic risk scores and epigenetic monitoring to implement early, targeted preventive interventions.