Lead exposure and preeclampsia in sub-Saharan Africa: modelling the potential contribution to maternal disease burden and opportunities for prevention

Abstract Background Hypertensive disorders of pregnancy, particularly preeclampsia, are a leading cause of maternal morbidity and mortality in sub-Saharan Africa (SSA). Although environmental lead exposure remains widespread across the region, its contribution to the burden of preeclampsia has not previously been quantified at the population level. Methods We conducted a modelling study using maternal blood lead level (BLL) data synthesised from pregnancy biomonitoring studies in SSA and supplemented these with soil-derived exposure scenarios representing severely contaminated environments. Biomonitoring data represented real-world exposure distributions, whereas soil-derived scenarios evaluated potential impacts in highly contaminated communities. Published meta-analytic evidence indicating a 1.6% increase in the odds of preeclampsia per 1 µg/dL increase in maternal BLL was used to estimate predicted preeclampsia risk across plausible baseline prevalence scenarios. Sensitivity analyses evaluated uncertainty associated with exposure extrapolation and baseline prevalence, and population attributable fractions (PAFs) were estimated. Results Maternal BLLs reported in SSA pregnancy studies ranged from 0.83 to 99.0 µg/dL, with a study-level mean of 26.24 µg/dL, approximately 10–40 times higher than maternal BLLs reported in North America, Europe and other high-income regions. Biomonitoring-derived BLLs were associated with modest but consistent increases in predicted preeclampsia risk. Estimated PAFs suggested that, if the observed association is causal, lead exposure could account for approximately 6–8% of preeclampsia cases at low exposure (∼5 µg/dL), 19–21% at typical urban exposure (∼15 µg/dL), and 41–47% in highly exposed populations (∼40 µg/dL). Relative exposure-response relationships remained robust across sensitivity analyses. Conclusions Maternal lead exposure is a potentially modifiable environmental risk factor for preeclampsia in SSA that has received little attention in maternal health policy. These findings support integrating lead exposure prevention, environmental remediation, and targeted maternal biomonitoring into maternal health programmes, particularly in high-risk settings, to reduce preventable preeclampsia and improve maternal health outcomes.