Placental Pathways: The Impact of Air Pollution (PM2.5) Exposure on Pregnancy Outcomes in three Sub-Saharan African Countries

IntroductionAmbient and indoor fine particle air pollution (PM2{middle dot}5) estimates have been associated with pregnancy complications. We aimed to link direct personal exposure measurements with placenta-mediated pregnancy complications in three sub-Saharan African countries. MethodsWe recruited a geographically and energy use stratified sub-sample of 343 rural and urban women who had recently given birth in the PREgnancy Care Integrating translational Science, Everywhere (PRECISE) prospective pregnancy cohort in The Gambia (n = 160), Kenya (n = 105), and Mozambique (n = 78). Individual-level exposure to PM2{middle dot}5 was assessed using high-resolution personal monitoring, during both wet and dry seasons. Minute-level data were summarised as mean and peak daily PM2{middle dot}5 concentrations, and correlated with maternal blood pressure (BP), gestational age at delivery, fetal growth, and stillbirth, in the index pregnancy. Results107/343 (32{middle dot}2%) women experienced pregnancy hypertension, 57/343 (16{middle dot}0%) women delivered preterm, 203/304 (66{middle dot}8%) infants with known birthweights were appropriately-grown, and 9/343 (2{middle dot}7%) infants were stillborn. Higher mean (p=0{middle dot}012) and peak (p=0{middle dot}007) exposures were associated with reduced fetal growth velocity, with greater mean exposure associated with small-for-gestational age infants (p=0{middle dot}016). Greater mean (p=0{middle dot}017) and peak (p=0{middle dot}045) PM{square}.{square} exposures were associated with lower birthweight centile. No associations were observed with pregnancy hypertension, pregnancy duration, or stillbirth. DiscussionThis study provides exploratory evidence that personal PM2{middle dot}5 exposure is associated with impaired fetal growth in sub-Saharan Africa. Prioritising access to clean fuels, reducing emissions from informal transport and waste systems, and incorporating personal exposure monitoring into maternal health frameworks could yield measurable improvements in birth outcomes and health equity.