Prenatal allostatic load and adverse pregnancy outcomes: a systematic review and meta-analysis.

BACKGROUND: Allostatic load (AL) denotes the cumulative physiological dysregulation resulting from chronic stress exposure. This systematic review and meta-analysis aimed to evaluate the association between prenatal AL and adverse pregnancy outcomes (APOs), and to synthesize current evidence to inform prenatal health strategies and potentially reduce the incidence of APOs. METHODOLOGY: This study systematically searched PubMed, Web of Science, Embase, PsycINFO, China National Knowledge Infrastructure, Wanfang, VIP China Science and Technology Journal Database, and SinoMed databases for relevant studies examining prenatal AL and APOs published from September 1993 to 22 June 2026. Two researchers independently screened the literature, extracted data, and assessed the risk of bias using the Newcastle-Ottawa scale. Meta-analysis was performed using R software (version 4.4.3). The study protocol is registered in PROSPERO (CRD420251076952). RESULTS: Eight original studies involving 8,795 pregnant women were included. High prenatal AL was associated with an increased risk of preterm birth (OR = 1.29, 95% CI [1.04-1.60]) and preeclampsia (OR = 2.31, 95% CI [1.42-3.76]). There was no statistically significant association with low birth weight (OR = 1.10, 95% CI [0.95-1.26]). Furthermore, exploratory subgroup analyses suggested that the gestational period and biomarker composition may influence these associations; however, high methodological heterogeneity limits direct clinical application. CONCLUSIONS: Elevated prenatal AL is associated with an increased risk of specific APOs, particularly preterm birth and preeclampsia. Future studies should adopt longitudinal designs with repeated AL measurements across pregnancy to clarify temporal dynamics and elucidate underlying biological mechanisms.