Estimating birthweight reduction attributable to maternal ozone exposure in low- and middle-income countries

The effect of O on birthweight in low- and middle-income countries (LMICs) remains unknown. A multicenter epidemiological study was conducted to evaluate the association between maternal peak-season O exposure and birthweight, using 697,148 singleton newborns obtained in 54 LMICs between 2003 and 2019. We estimated the birthweight reduction attributable to peak-season O exposure in 123 LMICs based on a nonlinear exposure-response function (ERF). With every 10-part per billion increment in O concentration, we found a reduction in birthweight of 19.9 g [95% confidence interval (CI): 14.8 to 24.9 g]. The nonlinear ERF had a monotonic decreasing curve, and no safe O exposure threshold was identified. The mean reduction in birthweight reduction attributable to O across the 123 LMICs was 43.8 g (95% CI: 30.5 to 54.3 g) in 2019. The reduction in O -related birthweight was greatest in countries in South Asia, the Middle East, and North Africa. Effective O pollution control policies have the potential to substantially improve infant health.