Prenatal lead exposure and risk of Pregnancy-Induced hypertension: A systematic review and Meta-Analysis.

BACKGROUND: Pregnancy-induced hypertension (PIH) affects up to 10% of pregnancies, and its incidence has been rising in recent years. Emerging evidence suggests that prenatal lead exposure, even at low concentrations, may be a potential risk factor for PIH. This systematic review and meta-analysis aims to evaluate the association between maternal blood lead levels and the risk of preeclampsia and gestational hypertension by synthesizing findings from multiple epidemiological studies. METHODS: A comprehensive literature search was conducted in Scopus, PubMed, and Web of Science for studies published between 1993 and 2023, using a combination of Medical Subject Headings (MeSH) terms and expert-defined keywords. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 5,918 titles were screened. Studies were included based on predefined eligibility criteria. A random-effects meta-analysis and linear regression were used to evaluate the association between prenatal lead exposure and pregnancy-induced hypertension outcomes. RESULTS: The analysis included cohort, case-control, and cross-sectional studies, with sample sizes ranging from 39 to 971 participants. Women with preeclampsia had significantly higher mean blood lead levels (18.4 µg/dL; 95% CI: 16.1-20.7) compared to normotensive controls (7.4 µg/dL; 95% CI: 6.2-8.6), resulting in a standardized mean difference (SMD) of 2.2 (95% CI: 1.8-2.6; p < 0.01). Considerable heterogeneity was observed across continents (I² = 92.5%), study designs (I² = 87.3%), and sample sizes (I² = 89.1%). Publication bias was identified using funnel plots and Egger's test (p < 0.05). Sensitivity analyses, excluding studies with extreme values, confirmed the robustness of the association. CONCLUSION: This meta-analysis provides compelling evidence that prenatal blood lead exposure is associated with an elevated risk of preeclampsia and gestational hypertension. These findings highlight the importance of proactive environmental monitoring and preventive clinical measures to minimize maternal lead exposure and enhance pregnancy outcomes.