Blood lead and preeclampsia: A meta-analysis and review of implications

Abstract

Background Multiple cross-sectional studies suggest that there is an association between blood lead and preeclampsia. Objectives We performed a systematic review and meta-analysis to summarize information on the association between preeclampsia and lead poisoning. Methods Searches of Medline, Web of Science, Scopus, Pubmed, Science Direct and ProQuest (dissertations and theses) identified 2089 reports, 46 of which were downloaded after reviewing the abstracts, and 11 studies were evaluated as meeting the selection criteria. Evaluation using the ROBINS-I template (Sterne, et al., 2016), indicated moderate risk of bias in all studies. Results We found that blood lead concentrations were significantly and substantially associated with preeclampsia (k = 12; N = 6069; Cohen's d = 1.26; odds ratio = 9.81; odds ratio LCL = 8.01; odds ratio UCL = 12.02; p = 0.005). Eliminating one study produced a homogeneous meta-analysis and stronger estimates, despite the remaining studies coming from eight separate countries and having countervailing risks of bias. Conclusions Blood lead concentrations in pregnant women are a major risk factor for preeclampsia, with an increase of 1 μg/dL associated with a 1.6% increase in likelihood of preeclampsia, which appears to be the strongest risk factor for preeclampsia yet reported. Pregnant women with historical lead exposure should routinely have blood lead concentrations tested, especially after mid-term. Women with concentrations higher than 5 μg/dL should be actively monitored for preeclampsia and be advised to take prophylactic calcium supplementation. All pregnant women should be advised to actively avoid lead exposure.