Maternal prenatal anxiety and risk of preterm birth and low birthweight: Evidence from a cumulative meta-analysis with stability thresholds

BACKGROUND: We conducted cumulative meta-analyses to quantify the degree to which maternal prenatal anxiety impacts preterm birth (PTB) and low birthweight (LBW), and to identify when findings reached stability, enabling confident recommendations for early interventions. METHODS: Following PRISMA guidelines, we systematically searched PubMed/MEDLINE, PsycINFO, Scopus, EMBASE, CINAHL (EBSCO), ProQuest, and the Cochrane Library from database inception to May 7, 2025. The methodological quality of included studies was assessed using the Newcastle-Ottawa Scale. Inverse variance weighted random-effects cumulative meta-analysis was performed to pool adjusted odds ratios (AORs) with sequential inclusion of newly published studies. Stability thresholds were computed to assess sufficiency and stability of the association over time. Failsafe ratio, relative change (%), and weighted regression (cumulative slope) were applied to further examine stability and consistency. The protocol was registered in PROSPERO (CRD420251025049). RESULTS: Forty observational studies published between 1996 and 2025, representing over 1.97 million mother-child pairs, were included. Maternal prenatal anxiety was associated with a higher risk of PTB (AOR = 1.41, 95% CI:1.27-1.58) and LBW (AOR = 1.32, 95% CI:1.16-1.51). The stability threshold indicated that a future new study would need to demonstrate an OR of 0.71 (95% CI limit:1.12) for PTB, and 0.76 (95% CI limit = 1.10) for LBW, to change the associations reported in the pooled results. CONCLUSIONS: Maternal prenatal anxiety was associated with higher risks of PTB and LBW, with these conclusions unlikely to be materially changed by future studies, suggesting the need for routine screening and early intervention to improve perinatal outcomes.