Prenatal exposure to fine particulate matter and fetal growth: a cohort study from a velocity perspective.

Background: Reduced growth velocity before birth increases the risk of adverse health outcomes in adult life. However, until recently, there has been a lack of studies demonstrating the impact of prenatal PM _2.5 exposure on fetal growth velocity.
Methods: The current study was embedded in a previous cohort built between January 1, 2014, and April 30, 2015, in Shanghai First Maternity and Infant Hospital, China, in 6129 eligible singleton pregnancies. The PM _2.5 concentration was estimated by an inverse distance weighted method according to the residential addresses of the participants. Repeated fetal biometry measurements, including head circumference (HC), abdominal circumference (AC), femur length (FL), and biparietal diameter (BPD), were measured through ultrasound between 14 and 41 gestational weeks. A principal component analysis through conditional expectation for sparse longitudinal data was used to estimate the corresponding velocities.
Results: A total of 22782 ultrasound measurements were conducted among 6129 participants with a median of 2 and a maximum of 9 measurements. With each 10 μg/m ³ increase in cumulative PM _2.5 exposure, the velocity of HC, AC FL and BPD decreased by 0.12 mm/week, 0.17 mm/week, 0.02 mm/week and 0.02 mm/week, respectively, on average. The results of the Generalized Functional Concurrent Model showed that the velocity decreased significantly with PM _2.5 exposure between 22 and 32 gestational weeks, which might be the potential sensitive exposure window.
Conclusions: There are negative associations between prenatal exposure to PM _2.5 and fetal growth velocity, and the late second trimester and early third trimester might be the potential sensitive window.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)