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 PM_2.5 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 PM_2.5 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 PM_2.5. An increase in PM_2.5 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 PM_2.5 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 PM_2.5. Our findings provide evidence that maternal PM_2.5 exposure increased SGA risk, especially during the late pregnancy.