Associations of prenatal exposure to fine particulate matter and its constituents with small for gestational age risk: A twin study in China.

This study aimed to examine the impact of PM2.5 and its constituents on small for gestational age (SGA). We collected records of 8082 twin pairs and their mothers from 21 hospitals across China. Concentrations of PM2.5 and its constituents were from the Tracking Air Pollution dataset. Generalized linear models were utilized in this observational study to explore the relationship between SGA and PM2.5. An increase in PM2.5 by one interquartile range during pregnancy was linked to a 17 % increased SGA risk (OR = 1.17, 95 % CI: 1.05-1.31), with a population attributable fraction of 18.97 % (95 %CI: 5.65 %, 30.93 %). Additionally, higher risk of SGA was associated with exposure to ammonium (OR=1.17, 95 %CI: 1.03-1.34), sulfate (OR=1.10, 95 %CI: 1.01-1.21), nitrate (OR=1.16, 95 %CI: 1.02-1.33), black carbon (OR=1.09, 95 %CI: 1.00-1.19), and organic matter (OR=1.11, 95 %CI: 1.00-1.23) during pregnancy. Similar associations were observed for SGA with PM2.5 and its constituents in late pregnancy (all P < 0.05). Furthermore, individuals conceived via assisted reproduction (OR = 1.22, 95 % CI: 1.03-1.43), with pregnancy complications (OR = 1.23, 95 % CI: 1.07-1.41), and residing in colder areas (OR = 1.20, 95 % CI: 1.02-1.40) shown more susceptible to PM2.5. Our findings provide evidence that maternal PM2.5 exposure increased SGA risk, especially during the late pregnancy.