Prenatal Exposure to Airborne Particulate Matter of 1 μm or Less and Fetal Growth: A Birth Cohort Study in Beijing, China.

Abstract Background The association of airborne particulate matter of 1 μm or less (PM1) with fetal growth hasn’t been studied. We aimed to investigate the association of PM1 with fetal growth parameters measured via ultrasonography and birth weight. Methods The birth cohort included 18,669 pregnant women who were pregnant between 2014 to 2017 in Tongzhou Maternal and Child Health Hospital of Beijing, China. The predicted PM1 concentration was matched with the residential addresses of each woman. The fetal abdominal circumference (AC), head circumference (HC), femur length (FL) and estimated fetal weight (EFW) were evaluated via ultrasonography, while birth weight was measured at birth. The fetal parameters and birth weight were standardized as gestational-age- and gender-adjusted Z-score. We defined undergrowth of fetal parameters, low birth weight (LBW) and small-for-gestational-age (SGA) as categorized outcomes. Generalized estimating equations and generalized linear regression were used to examine the associations of PM1 with quantitative and categorized outcomes, respectively. Results A 10 μg/m3 increase in PM1 was associated with decrement in the Z-scores of AC [ 0.027, 95%CI: 0.047∼ 0.007], HC ( 0.054, 95%CI: 0.074∼ 0.034), FL ( 0.067, 95%CI: 0.087∼ 0.046) and EFW ( 0.055, 95% confidence intervals (CI): 0.075∼ 0.035). These results remained robust after adjusting nitrogen dioxide and sulfur dioxide. We didn’t observe significant results regarding the analyses of undergrowth of all fetal parameters and the analyses of birth weight outcomes. Conclusion This study identified the negative associations between PM1 and fetal parameters in utero. The findings provided robust evidence that strategies for reducing PM1 exposure can prevent early-life health.