Prenatal exposure to airborne particulate matter of 1 μm or less and fetal growth: A birth cohort study in Beijing, China.

Background: The association of airborne particulate matter of 1 μm or less (PM) with fetal growth hasn't been studied. We aimed to investigate the association of PM with fetal growth parameters measured via ultrasonography and birth weight.

Methods: The birth cohort included 18,669 pregnant women who were pregnant between 2014 and 2017 in Tongzhou Maternal and Child Health Hospital of Beijing, China. The predicted PM 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 PM with quantitative and categorized outcomes, respectively.

Results: A 10 μg/m increase in PM was associated with decrement in the Z-scores of AC [-0.027, 95% confidence intervals (CI): -0.047~ -0.07]EFW (-0.055, 95%CI: -0.075~-0.035). These results remained robust after adjusting nitrogen dioxide and sulphur 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 PM and fetal parameters in utero. The findings provided robust evidence that strategies for reducing PM exposure can prevent early-life health.