Global, regional, and national burden of preterm birth attributable to ambient and household PM2.5 from 1990 to 2019: Worsening or improving?

Background: Maternal exposure to fine particular matter (PM2.5) during pregnancy, including ambient and household PM2.5, has been linked with increased risk of preterm birth (PTB). However, the global spatio-temporal distribution of PTB-related deaths and disability-adjusted life years (DALYs) attributable to PM2.5 is not well documented. We esti-mated the global, regional, and national patterns and trends of PTB burden attributable to both ambient and household PM2.5 from 1990 to 2019.Methods: Based on the Global Burden of Disease Study (GBD) 2019 database, we obtained the numbers of deaths and DALYs as well as age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) of PTB attributable to total, ambient, and household PM2.5 by socio-demographic index (SDI) and sex during 1990-2019. The average an-nual percentage changes (AAPCs) were calculated to assess the temporal trends of attributable burdens.Results: In 2019, 126,752 deaths and 11.3 million DALYs related to PTB worldwide (two-thirds in Western Sub-Saharan Africa and South Asia) could be caused by excess PM2.5 above the theoretical minimum-risk exposure level (TMREL), of which 39 % and 61 % were attributable to ambient PM2.5 and household PM2.5, respectively. From 1990 to 2019, the global ASMR due to ambient PM2.5 increased slightly by 7.08 % whereas that due to household PM2.5 decreased substantially by 58.81 %, although the latter still dominated the attributable PTB burden, especially in low and low-middle SDI regions. Similar results were also observed for ASDRs. In addition, PTB burden due to PM2.5 was higher in male infants and in lower SDI regions.