The associations between birth weight and exposure to fine particulate matter (PM2.5) and its chemical constituents during pregnancy: A meta-analysis

Abstract

We performed this meta-analysis to estimate the associations of maternal exposure to PM2.5 and its chemical constituents with birth weight and to explore the sources of heterogeneity in regard to the findings of these associations. A total of 32 studies were identified by searching the MEDLINE, PUBMED, Embase, China Biological Medicine and Wanfang electronic databases before April 2015. We estimated the statistically significant associations of reduced birth weight (β = -15.9 g, 95% CI: -26.8, -5.0) and LBW (OR = 1.090, 95% CI: 1.032, 1.150) with PM2.5 exposure (per 10 μg/m(3) increment) during the entire pregnancy. Trimester-specific analyses showed negative associations between birth weight and PM2.5 exposure during the second (β = -12.6 g) and third (β = -10.0 g) trimesters. Other subgroup analyses indicated significantly different pooled-effect estimates of PM2.5 exposure on birth weight in studies with different exposure assessment methods, study designs and study settings. We further observed large differences in the pooled effect estimates of the PM2.5 chemical constituents for birth weight decrease and LBW. We concluded that PM2.5 exposure during pregnancy was associated with lower birth weight, and late pregnancy might be the critical window. Some specific PM2.5 constituents may have larger toxic effects on fetal weight. Exposure assessment methods, study designs and study settings might be important sources of the heterogeneity among the included studies.

Association between PM2.5 and PM2.5 Constituents and Preterm Delivery in California, 2000–2006

“…A recent meta-analysis using results from a number of previous studies found that Zn, Ti, V, OC, NO 3 À , EC, K, NH 4 + , Si and S were associated with LBW. 34 In this study, we found Blacks, Asians and older mothers had trends for greater associations with some PM 2.5 constituents. These subgroups may live closer to monitoring stations than others or have the highest exposure to PM 2.5 and its particular constituents.…”

“…found increased risk of term LBW associated with EC, Br, NH 4 + and other constituents in California. A recent meta‐analysis using results from a number of previous studies found that Zn, Ti, V, OC, NO 3 − , EC, K, NH 4 + , Si and S were associated with LBW …”

Associations of Short-Term and Long-Term Exposure to Ambient Air Pollutants With Hypertension

“…The heterogeneity between the included studies may reflect differences in the study settings, study design, exposure assessment, constituents of PM, and confounder adjustment, which may influence the variation in exposure to air pollution and potentially cause different dose-response relationships. 46,47 In addition, we found that age was negatively associated with effect sizes of air pollution, which indicated that age might be an important source of heterogeneity between studies. The protective effect of age might be related to the different medication use between young age and elderly.…”

Maternal residential air pollution and placental imprinted gene expression

“…Genomic imprinting arises early in fetal development and it has been suggested that these epigenetic patterns may function as a biosensor for the impact of in utero environmental exposures (Hoyo et al 2009; Jirtle and Skinner 2007). In addition, imprinting plays an important role in fetal development and growth, a process that has been found to be disrupted by exposure to air pollutants (Dadvand et al 2013; Lamichhane et al 2015; Sapkota et al 2010; Stieb et al 2012; Sun et al 2016; Zhu et al 2015). …”

“…Maternal exposure to ambient air pollution during fetal development has been associated with reduced fetal growth, even at exposure levels lower than National Ambient Air Quality Standards (Dadvand et al 2013; Lamichhane et al 2015; Sapkota et al 2010; Stieb et al 2012; Sun et al 2016; Zhu et al 2015). However, the underlying molecular mechanisms remain unknown.…”