Allostatic load in reproductive medicine: A review and narrative synthesis across infertility, ART, and pregnancy outcomes

Objective To synthesize available evidence on allostatic load and reproductive outcomes, evaluate methodological heterogeneity, identify knowledge gaps, and propose a harmonized biomarker framework for reproductive medicine research. Design Focused narrative review of the literature. Materials and Methods We searched PubMed/MEDLINE, Web of Science, Scopus, and the Cochrane Library from inception to April 5, 2026, supplemented by citation chasing. Eligible studies reported an operationalized allostatic load composite and evaluated reproductive endpoints or provided methodological insight relevant to allostatic load measurement during pregnancy. Results Thirteen publications were included: seven primary empirical reproductive outcome studies, two construct-validity studies, one systematic review, and three narrative or methodological reviews. In the AMIGOS trial-embedded infertility cohort (n=836), preconception allostatic load was not associated with conception or live birth, but higher allostatic load was associated with preeclampsia and preterm birth among women who achieved live birth. In a cross-sectional NHANES analysis (n=419; 59 infertile, 360 controls), allostatic load was higher in women with infertility than in controls (p=0.029). In the nuMoM2b prospective cohort (n=4,266), first-trimester allostatic load was associated with higher odds of composite adverse pregnancy outcomes, particularly hypertensive disorders of pregnancy (aOR 1.50, 95% CI 1.3–1.7; HDP aOR 2.5, 95% CI 2.0–2.9). In a matched case-control study (38 cases, 75 controls), preeclampsia was associated with higher allostatic load (1.25 vs 0.83, p=0.002; OR 2.91, 95% CI 1.50–5.65). Across studies, biomarker panels ranged from five to twelve components, scoring approaches varied widely, and pregnancy-related physiological changes complicated construct validity. Conclusion Emerging but limited evidence suggests that elevated allostatic load may be associated more consistently with adverse pregnancy outcomes, especially hypertensive disorders of pregnancy, than with infertility or ART success. Standardized biomarker selection and measurement timing are needed before allostatic load can be used meaningfully in reproductive medicine research or risk stratification.