Effects of PM2.5 and its constituents on hemoglobin during the third trimester in pregnant women

Abstract

Anemia has been a public health issue evoking global concern, and the low hemoglobin (Hb) concentration links to adverse pregnancy outcomes. However, the associations of PM2.5 and its constituents with Hb and anemia in pregnant women remain unclear. In this retrospective birth cohort study, 7932 pregnant women who delivered in the First Affiliated Hospital of Xi’an Jiaotong University from 2015 to 2018 were included. The Hb during the third trimester in pregnant women was assessed before delivery. PM2.5 and its constituents (BC, NH4+, NO3−, OM, SO42−, and Dust) during pregnancy were retrieved from the V4.CH.03 product constructed by the Atmospheric Composition Analysis Group. Generalized linear regression model was applied to investigate the effects of PM2.5 and its constituents on Hb and anemia during the third trimester in pregnant women. The means and standard deviations of PM2.5, BC, NH4+, NO3−, OM, SO42−, and Dust were 69.56 (15.24), 10.02 (2.72), 8.11 (1.77), 14.96 (5.42), 15.36 (4.11), 10.08 (1.20), and 10.98 (1.85) μg/m3, respectively. Per IQR increase (μg/m3) of PM2.5, BC, NO3−, and OM linked to − 0.75 (− 1.50, − 0.01), − 0.85 (− 1.65, − 0.04), − 0.79 (− 1.56, − 0.03), and − 0.73 (− 1.44, − 0.03) g/L decrease of Hb during the third trimester in multiparous pregnant women, but not for NH4+, SO42−, Dust, and primiparous pregnant women. PM2.5 and its constituents had no significant association with anemia, except for Dust (OR: 0.90, 95% CI: 0.82, 0.99, per IQR increase) in primiparous pregnant women. Besides, SO42− was of lag effects on Hb and anemia in multiparous pregnant women. Moreover, non-linear associations were found among PM2.5 and its constituents, Hb, and anemia. Therefore, exposure to PM2.5 and some constituents of PM2.5 was associated with reduced Hb level during the third trimester in multiparous pregnant women. Related departments and pregnant women should take targeted actions to eliminate the detrimental effects of PM2.5 and its constituents on pregnancy outcomes.

Association of ambient air pollution with hemoglobin levels and anemia in the general population of Korean adults

“…Previous epidemiological studies have identified significant relationships between exposure to ambient air pollutants and decreased hemoglobin or anemia, mainly in certain populations such as the elderly, children, and pregnant women [ 9 – 13 , 31 ]. In 2017, Honda et al reported that long-term exposure to PM 2.5 and NO 2 was positively associated with anemia prevalence and decreased hemoglobin levels in older American adults [ 10 ].…”

“…In recent years, a growing body of evidence has also shown the detrimental effects of air pollution exposure on hemoglobin concentrations and anemia in specific populations (i.e., children, pregnant women, and the elderly) [ 9 – 13 ]. Ambient air pollution, which is a complex mixture of liquid droplets, gases, and solid particles, contributes to disturbances in iron homeostasis [ 14 ].…”

Non-linear connections between maternal hemoglobin during the third trimester of pregnancy and birth weight outcomes in full-term newborns: Estimating the breakpoints

“…In this study, the breakpoints of the non-linear connection between maternal hemoglobin and birth weight outcomes were estimated to range from 97 to 138 g/L, which were incongruent with the widely used cutoff value of anemia in pregnancy put forward by WHO ( 2 ). Indeed, hemoglobin concentration is influenced by multi-facet factors ( 4 , 36 – 38 ). Hemoglobin concentration declines with the increase in altitude in response to the declined blood oxygen saturation in high altitude places ( 36 ).…”

“…Carbon monoxide in tobacco smoke can promote the formation of carboxyhemoglobin in red blood cells and induce a compensatory increase in hemoglobin ( 37 ). In addition, lower hemoglobin concentrations are associated with low socioeconomic status, imbalanced dietary patterns, multiparity, and high concentration exposure to air pollution ( 4 , 38 ). Thus, the cutoff value of hemoglobin concentration for anemia in pregnancy should be reevaluated according to different conditions, so as to avoid the misclassification of anemia.…”

“…The mainstream diagnostic standard for anemia in pregnancy is that Hb concentration is lower than 110 g/L at any period during pregnancy, which is put forward by the World Health Organization (WHO), and it is beneficial to compare the prevalence of anemia in pregnancy across countries and territories (2). Given that Hb concentration varies with altitude, dietary patterns, iron supplements, smoking, and environment, the aforementioned diagnostic standard may be not suitable for all conditions (3)(4)(5). For example, US Centers for Disease Control and Prevention proposes the dynamic diagnostic standard for anemia in pregnancy, and the cutoff value is of Hb concentration for the diagnosis of anemia in pregnancy are 110, 105, and 110 g/L in the first, second, and third trimesters, respectively (6).…”