Risk Factors for Preterm Delivery and Low Birth Weight: An Umbrella Review of Meta-Analysis

Abstract

Background: Low birth weight (LBW) and preterm birth (PTB) are significant global health challenges associated with increased neonatal morbidity and mortality. This review aimed to comprehensively evaluate maternal, socioeconomic, and neonatal risk factors for LBW and PTB to inform clinical practice and public health interventions.

Method: We conducted a systematic review of meta-analyses published through February 2025. PubMed, Scopus, Web of Science, and Cochrane databases were searched for meta- analyses of observational studies examining risk factors for LBW (<2500g) and PTB (<37 weeks of gestation). Risk factors were categorized by evidence level (robust, highly suggestive, suggestive, or weak) based on statistical significance, sample size, heterogeneity, and potential biases. Random-effects models were used to calculate pooled odds ratios (ORs) with 95% confidence intervals (CIs).

Result: Our analysis included 86 meta-analyses encompassing 1,511 primary studies. For LBW, the strongest risk factors were maternal hypertension (OR 3.90, 95% CI 2.73-5.58), crack/ cocaine use (OR 2.82, 95% CI 2.26-3.52), and periodontal disease (OR 2.41, 95% CI (1.67-3.47). For PTB, placenta previa (OR 5.32, 95% CI 4.39-6.45), amphetamine exposure (OR 3.59, 95% CI 2.09-6.17) and chronic hypertension (OR 2.47, 95% CI 1.98-3.07) showed the strongest associations. Seven risk factors demonstrated robust evidence for PTB, while most LBW risk factors provided suggestive evidence. Medical conditions and substance use represented the largest categories of risk factors for both outcomes.

Conclusion: This umbrella review identified multiple modifiable risk factors for LBW and PTB with varying levels of evidence. Maternal hypertension, substance use, and periodontal disease emerged as key targets for intervention. Integrated prenatal care addressing both medical and psychosocial factors may help reduce the burden of adverse birth outcomes. Future research should focus on interventions targeting modifiable risk factors with robust evidence.