Household Air Pollution Linked to Anemia Risk in Pregnant Women

Exposure to common household air pollution, particularly carbon monoxide (CO), has been linked to higher hemoglobin levels and lower anemia prevalence among pregnant women, according to analysis of the Household Air Pollution Intervention Network (HAPIN) trial.¹

On the other hand, according to the investigative team from Emory University, exposure to fine particular matter (PM_2.5) in pregnant women demonstrated associations in the opposite direction, with lower hemoglobin levels and a higher likelihood of anemia.

“Our findings offer quantitative evidence for the association of air pollution exposure, as characterized by personal PM_2.5, CO, and black carbon exposure, rather than relying on self-reported use of various cooking or heating fuels or ambient air pollution monitoring data, on the hemoglobin levels and prevalence of anemia among pregnant women,” wrote the investigative team, led by Yanling Deng, Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University.

Anemia is among the most prevalent complications during pregnancy—approximately 36% of pregnant women had anemia in 2019, with the greatest prevalence in low- and middle-income countries.² Evidence has found the effect of environmental pollutants, aside from dietary iron deficiency, could contribute to anemia rates.³

Cooking with solid fuels results in household air pollution, including fine particulate matter and CO, marking a significant, prevalent environmental risk factor for adverse health outcomes.⁴

Prior research has linked ambient air pollution to changes in hemoglobin levels and anemia status among pregnant women.⁵ Other research has linked household air pollution from cooking fuels with an increased risk of anemia among non–pregnant reproductive-aged women.⁶

However, there are few investigations into an exposure-response relationship between pollution and hemoglobin levels, despite the need to understand the degree of exposure reduction required for health improvement.¹ In this analysis, Deng and colleagues used baseline data from HAPIN to evaluate the association of exposure to air pollutants with hemoglobin levels and anemia in pregnant women.

This analysis of HAPIN studied 3,163 pregnant women aged 18 to 35 years, with 9 to 20 weeks gestation, across four Intervention Research Centers (IRCs) in rural areas of Guatemala, India, Peru, and Rwanda. Investigators measured 24-hour personal exposure to fine particulate matter, black carbon, and CO, as well as hemoglobin levels at baseline (~15 weeks gestation).

Multivariable linear models investigated the association between pollutant exposure with hemoglobin levels, while logistic regression models evaluated the association with anemia prevalence.

Among the 3,136 pregnant women, 853 (51.8%) were characterized as having anemia. Single-pollutant models revealed an association between an interquartile range (IQR) increase in CO (2.26 ppm) with higher hemoglobin levels and a lower prevalence of anemia.

Bipollitant analysis also demonstrated an IQR increase in CO concentrations (2.26 ppm) with 0.04 g/dL higher hemoglobin levels (95% CI, 0.01 – 0.07; P = .009). A higher IQR CO level (2.26 ppm) was also linked to a lower risk of anemia prevalence (odds ratio [OR], 0.90 [95% CI, 0.83 – 0.98]; P = .02).

Meanwhile, PM_2.5 was inversely related to hemoglobin levels. An IQR increase in PM_2.5 levels (99.4 µm/m3) was associated with 0.02 g/dL lower hemoglobin levels (95% CI, –0.06 to 0.03; P = .45), but this association was not statistically significant at the 0.05 alpha level.

On the other hand, an IQR higher PM_2.5 level (99.4 µm/m3) was associated with a higher risk of anemia (OR, 1.03; 95% CI, 0.95 – 1.12; P = .48), but again, this association did not reach statistical significance.

Models evaluating the effect by study site revealed a similar association between CO and hemoglobin levels, and anemia prevalence, but this was observed only in Rwanda (P = .06). Deng and colleagues identified no evidence of a positive or inverse association between black carbon and hemoglobin levels or anemia prevalence.

“Our findings provide support for the ongoing efforts to address exposure to household air pollution in conjunction with other factors contributing to lower hemoglobin levels in low- and middle-income countries,” they wrote.

References

1. _{Deng Y, Steenland K, Sinharoy SS, et al. Association of household air pollution exposure and anemia among pregnant women: Analysis of baseline data from ‘Household Air Pollution Intervention Network (HAPIN)’ trial. Environ Int. Published online June 13, 2024. doi:10.1016/j.envint.2024.108815}
2. _{Stevens GA, Paciorek CJ, Flores-Urrutia MC, et al. National, regional, and global estimates of anaemia by severity in women and children for 2000-19: a pooled analysis of population-representative data. Lancet Glob Health. 2022;10(5):e627-e639. doi:10.1016/S2214-109X(22)00084-5}
3. _{Cai J, Li Y, Liu S, et al. Associations between multiple heavy metals exposure and glycated hemoglobin in a Chinese population. Chemosphere. 2022;287(Pt 2):132159. doi:10.1016/j.chemosphere.2021.132159}
4. _{Clasen TF, Chang HH, Thompson LM, et al. Liquefied Petroleum Gas or Biomass for Cooking and Effects on Birth Weight. N Engl J Med. 2022;387(19):1735-1746. doi:10.1056/NEJMoa2206734}
5. _{Xie G, Yue J, Yang W, et al. Effects of PM2.5 and its constituents on hemoglobin during the third trimester in pregnant women. Environ Sci Pollut Res Int. 2022;29(23):35193-35203. doi:10.1007/s11356-022-18693-2}
6. _{Kwag Y, Oh J, Yang W, Kim Y, Ha EH, Ye S. Effect of PM concentration on anemia blood indicators reduced by air purifiers. Chemosphere. 2023;323:138131. doi:10.1016/j.chemosphere.2023.138131}