Maternal exposure to fine particulate matter and preterm birth and low birth weight in Africa

Fine particulate matter (PM_2.5) exposure has been reported to adversely affect birth outcomes, but the evidence is limited, particularly in low- and middle-income countries (LMICs). We assessed the associations between maternal PM_2.5 exposure and low birth weight (LBW) and preterm birth (PTB) in Africa.

We used standard Demographic and Health Surveys (DHS) data (2005-2015) from 15 countries in Africa to conduct a cross-sectional study. The study population was composed of 131,594 births with detailed information on maternal and household variables. LBW was defined as a birth weight of < 2500 g after 37 weeks, and PTB was defined as live birth occurring before 37 weeks of gestation. Average exposure to PM_2.5 during pregnancy was estimated using satellite-based models. Multivariable logistic regression models were constructed, and analyses of data by region (Western, Eastern, Central, and Southern Africa) and data stratified by potential effect modifiers were conducted.

A total of 13,214 (10%) LBW and 4,377 (3.3%) PTB cases were identified. An interquartile range (IQR) (33.9 μg/m³) increase in PM_2.5 during pregnancy was associated with increased odds of LBW and PTB, with odds ratios (ORs) of 1.28 (95% CI: 1.23, 1.34) and 1.08 (95% CI: 1.01, 1.16), respectively. Region-specific analyses revealed significant associations between PM_2.5 and LBW in all regions, and significant associations between PM_2.5 and PTB in Western and Southern Africa. Subgroup analyses revealed that the association between PM_2.5 and LBW was present in all subgroups, and stronger associations were observed in female infants, while the association between PM_2.5 and PTB was larger in subgroups of older individuals living in urban areas.

This multicountry study in Africa demonstrated significant associations between maternal exposure to PM_2.5 and higher odds of LBW and PTB. Our findings may facilitate air quality control strategies that address adverse birth outcomes in LMICs.