Ghosh R, Causey K, Burkart K, et al. - Decreased birth weight and gestational age (GA) were evident in relation to ambient and household particulate matter <2.5 micrometer (PM _2.5 ), which in turn leads to neonatal and infant mortality, particularly in low- and middle-income countries.

• PubMed, Embase, and Web of Science were explored, and a meta-regression (MR) was conducted to quantify the risk of PM _2.5 on birth weight and GA.

• The MR involved 44, 40, and 40 birth weight, low birth weight (LBW), and preterm birth (PTB) studies, respectively.

• According to pooled estimates, per 10 μg/m ³ increase in ambient PM _2.5 resulted in 22 grams lower birth weight, 11% greater risk of LBW (1.11), and 12% greater risk of PTB (1.12).

• In 2019, a global population–weighted mean lowering of 89 grams of birth weight and 3.4 weeks of GA due to total PM _2.5 was estimated.

• On a global level, an estimated 15.6% of all LBW and 35.7% of all PTB infants were because of total PM _2.5 , equal to 2,761,720 and 5,870,103 infants in 2019, respectively.

• Ambient exposure could account for approximately one-third of the total PM _2.5 burden for LBW and PTB, with household air pollution predominant in low-income countries.