Early-life exposure to air pollutants and adverse pregnancy outcomes: protocol for a prospective cohort study in Beijing

Abstract

IntroductionThe association between early exposure to ambient air pollution and adverse pregnancy outcomes in China is unclear. This study will assess the risk of early-life exposure to air pollutants in Beijing and explore the viability of 8-hydroxydeoxyguanosine (8-OHdG) as a biological indicator to assess oxidative stress induced by early-life exposure to air pollution.Methods and analysisHere, 2500 women with singleton pregnancies and their infants will be recruited from the Beijing Obstetrics and Gynecology Hospital. We will collect nine types of biological samples, including maternal serum, urine, placental tissue, umbilical cord tissue and umbilical cord blood during all three trimesters. The air pollution data (particulate matter (PM)2.5, PM10 and similar factors) will be recorded at official fixed-site monitoring stations closest to where the pregnant women live. We plan to assess the effect of air pollutants on adverse pregnancy outcomes and infant respiratory and circulatory disease using Cox regression and competitive risk analysis and explore possible critical windows of exposure during pregnancy using daily pollutant concentrations averaged over various periods of pregnancy combined with individual activity and physiological parameters. Maternal and umbilical cord blood samples (1000 samples) will be randomly selected for 8-OHdG assays to assess the correlation between exposures to air pollutants and oxidative stress. We will determine whether air pollutant exposure or 8-OHdG levels are associated with adverse pregnancy outcomes. SPSS and SAS statistical software will be used for data analysis. Cox regression and competing risk analysis will be used to compute the HR and population attributable risk.Ethics and disseminationThis research protocol has already been approved by the Medical Ethics Committee of Beijing Obstetrics and Gynecology Hospital. Written informed consent will be obtained from all study participants prior to enrolment. The results will be published in peer-reviewed journals or disseminated through conference presentations.Trial registration numberThis study has been registered in WHO International Clinical Trial Register—Chinese Clinical Trial Registry under registrationnumber ChiCTR-ROC-16010181 (http :// www.chictr.org.cn / showproj.aspx ?proj=17328).

Maternal exposure to O3 and NO2 may increase the risk of newborn congenital hypothyroidism: a national data-based analysis in China

“…Maternal exposure to air pollution such as nitrogen oxides (NO x ), sulfur dioxide (SO 2 ), ozone (O 3 ), and particulate matter (PM) before or during pregnancy was associated with maternal complications such as gestational diabetes mellitus (GDM) and gestational hypertension disease (Fleisch et al 2014 ; Hooven et al 2011 ; Malmqvist et al 2013 ; Robledo et al 2015 ; Wang et al 2013 ; Wu et al 2011 ), and it was found to be consistently associated with abortion and stillbirth (Dastoorpoor et al 2018 ; Yang et al 2018 ). For offspring, maternal exposure to air pollution might cause small for gestational age (SGA), preterm birth (PTB), coarctation of the aorta, tetralogy of Fallot, and other congenital anomalies (Ballester et al 2010 ; Nieuwenhuijsen et al 2013 ; Song et al 2017 ; Vrijheid et al 2011 ). Disease and economic afford from adverse pregnancy outcomes caused by air pollution was enormous which should be valued.…”

The association between ambient air pollution and birth defects in four cities in Hunan province, China, from 2014 to 2016

“…Therefore, an increasing number of studies have examined the effects of air pollution on birth defects in China. [10–14] The study in Xi’an, China, used a generalized additive model to investigate the relationship between birth defects and ambient air pollutants, showed nitrogen dioxide (NO 2 ) increased risk of neural tube defects, congenital heart disease, congenital polydactyly, cleft palate, digestive system abnormalities and gastroschisis, and PM 10 was associated with congenital heart disease and cleft lip with or without cleft palate. [10] The hospital-based case-control study in Fuzhou, China, showed some positive associations between maternal exposure to ambient particles with an aerodynamic diameter of 10 mm or less (PM 10 ) during the first 2 months of pregnancy and fetal cardiovascular malformations.…”

Air Pollution and Racial Disparities in Pregnancy Outcomes in the United States: A Systematic Review

“…Almost all the studies we reviewed were large retrospective cohort studies, therefore, such other factors likely at least partially explain the disparities observed in the studies reviewed. We point, however, to evidence from molecular epidemiology studies that suggest biological mechanisms to explain the effects of air pollution on pregnancy outcomes (43)(44)(45). There is little data to suggest that Black mothers have any greater genetic predisposition to adverse effects of air pollution than Whites (26,28,45).…”