Combined exposure to PM2.5 and PM10 in reductions of physiological development among preterm birth: a retrospective study from 2014 to 2017 in China

Abstract

Background: Preterm birth (PTB) has been linked with ambient particulate matter (PM) exposure. However, data are limited between physiological development of PTB and PM exposure.

Methods: Trimester and season-specific PM exposure including PM_2.5 and PM₁₀ was collected from Jiaxing between January 2014 and December 2017. Information about parents and 3,054 PTB (gestational age < 37 weeks) outcomes such as weight (g), head circumference (cm), chest circumference (cm), height (cm) and Apgar 5 score were obtained from birth records. We used generalized linear models to assess the relationship between PTB physiological developmental indices and PM_2.5, PM₁₀ and their combined exposures. A binary logistic regression model was performed to assess the association between exposures and low birth weight (LBW, < 2,500 g).

Results: Results showed that there were 75.5% of low birth weight (LBW) infants in PTB. Decreased PM_2.5 and PM₁₀ levels were found in Jiaxing from 2014 to 2017, with a higher PM₁₀ level than PM_2.5 each year. During the entire pregnancy, the highest median concentration of PM_2.5 and PM₁₀ was in winter (61.65 ± 0.24 vs. 91.65 ± 0.29 μg/m³) followed by autumn, spring and summer, with statistical differences in trimester-specific stages. After adjusting for several potential factors, we found a 10 μg/m³ increase in joint exposure of PM_2.5 and PM₁₀ during the entire pregnancy associated with reduced 0.02 week (95%CI: -0.05, -0.01) in gestational age, 7.9 g (95%CI: -13.71, -2.28) in birth weight, 0.8 cm in height (95%CI: -0.16, -0.02), 0.05 cm (95%CI: -0.08, - 0.01) in head circumference, and 0.3 (95%CI: -0.04, -0.02) in Apgar 5 score, except for the chest circumference. Trimester-specific exposure of PM_2.5 and PM₁₀ sometimes showed an opposite effect on Additionally, PM_2.5 (OR = 1.37, 95%CI: 1.11, 1.68) was correlated with LBW.

Conclusion: Findings in this study suggest a combined impact of fine particulate matter exposure on neonatal development, which adds to the current understanding of PTB risk and health.

Keywords: PM10; PM2.5; birth outcomes; low birth weight; preterm birth.

Figure 1

Air pollutant concentrations of Jiaxing city in 2014–2017. (A) The box plot of PM_2.5 and PM₁₀ concentrations in different years. The upper and lower bars were the minimum and maximum values. (B) PM_2.5 and PM₁₀ concentration distributions compared with near cities in 2017. The color scheme indicates the degree of pollution. ^* p < 0.05; ^** p < 0.001.

Figure 2

An estimated change of every 1 μg/m³ increment of PM_2.5, PM₁₀ and joint exposure for physiological indicators during different pregnancy periods. (A) Gestational age; (B) Weight; (C) Height; (D) Head circumference; (E) Chest circumference; (F) Apgar 5 score. The joint exposure indicated the interaction effect of PM_2.5 and PM₁₀, which was calculated by the product of PM_2.5 and PM₁₀ concentrations (PM_2.5 * PM₁₀) to evaluate the additive effect. Models for gestation were adjusted for covariates of mother education level, father smoking, maternal age, delivery times, and other models were adjusted for mother education level, father smoking, gestational age, maternal age and delivery times. The blue and red line presents unadjusted and adjusted models, respectively.