Stillbirths Associated with Particle Pollution are Disproportionally Contributed by Sand Dust: Findings from 52 Low- and Middle-Income Countries.

Whether maternal exposure to dust-sourced particulate matter (hereafter, dust PM 2.5 ) is associated with stillbirth remains unknown. We adopted a sibling-matched case-control design to analyze 9332 stillbirths and 17,421 live births. We associated the risk of stillbirth simultaneously with dust and nondust components of PM 2.5 and developed a nonlinear joint exposure-response function. Next, we estimated the burden of stillbirths attributable to the PM 2.5 mixture. The concentration index was used to evaluate whether the burden of PM 2.5 -related stillbirths was disproportionally distributed among pregnancies exposed to dust-rich particles. Each 10 μg/m 3 increase in dust PM 2.5 was associated with a 14.5% (95% confidence interval: 5.5, 24.2%) increase in the odds of stillbirth. Based on the risk assessment across 137 countries, sand dust contributed to about 15% of the PM 2.5 exposure but to about 45% of the PM 2.5 -related stillbirths during 2003-2019. In 2015, 30% of the PM 2.5 -related stillbirths were concentrated within 15% of pregnancies exposed to the dust-richest PM 2.5 . The index increased in subregions, such as South Asia, suggesting the growth of health inequality due to exposure to dust PM 2.5 . Based on our findings, land management, such as halting desertification, will help prevent stillbirths and reduce global maternal health inequality.