1. Epidemiology and Global Health
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Exposure to landscape fire smoke reduced birthweight in low- and middle-income countries: findings from a siblings-matched case-control study

  1. Jiajianghui Li
  2. Tianjia Guan
  3. Qian Guo
  4. Guannan Geng
  5. Huiyu Wang
  6. Fuyu Guo
  7. Jiwei Li
  8. Tao Xue  Is a corresponding author
  1. Peking University, China
  2. Chinese Academy of Medical Sciences and Peking Union Medical College, China
  3. School of Energy and Environmental Engineering, University of Science and Technology Beijing, China
  4. School of Environment, Tsinghua University, Beijing, China, China
  5. College of Computer Science and Technology, Zhejiang University, China
Research Article
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Cite this article as: eLife 2021;10:e69298 doi: 10.7554/eLife.69298

Abstract

Landscape fire smoke (LFS) has been associated with reduced birthweight, but evidence from low- and middle-income countries (LMICs) is rare. Here, we present a sibling-matched case-control study of 227,948 newborns to identify an association between fire-sourced fine particulate matter (PM2.5) and birthweight in 54 LMICs from 2000 to 2014. We selected mothers from the geocoded Demographic and Health Survey with at least two children and valid birthweight records. Newborns affiliated with the same mother were defined as a family group. Gestational exposure to LFS was assessed in each newborn using the concentration of fire-sourced PM2.5. We determined the associations of the within-group variations in LFS exposure with birthweight differences between matched siblings using a fixed-effects regression model. Additionally, we analyzed the binary outcomes of low birthweight (LBW) or very low birthweight (VLBW). According to fully adjusted models, a 1 µg/m3 increase in the concentration of fire-sourced PM2.5 was significantly associated with a 2.17 g (95% confidence interval [CI]: 0.56-3.77) reduction in birthweight, a 2.80% (95% CI: 0.97-4.66) increase in LBW risk, and an 11.68% (95% CI: 3.59-20.40) increase in VLBW risk. Our findings indicate that gestational exposure to LFS harms fetal health.

Data availability

All data analysed during this study are included in the manuscript are from publicly sources, and their accesses are included in the manuscript and supporting files. Specifically, the health data can be directly accessed from the Demographic and Health Surveys website, https://www.dhsprogram.com/, after a free registration.

The following previously published data sets were used
    1. ICF
    (2014) Demographic and Health Surveys
    Not applicable (No DOI for DHS database).

Article and author information

Author details

  1. Jiajianghui Li

    Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
  2. Tianjia Guan

    School of Public Health, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7820-2898
  3. Qian Guo

    School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
  4. Guannan Geng

    School of Environment, Tsinghua University, Beijing, China, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
  5. Huiyu Wang

    Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
  6. Fuyu Guo

    Peking University, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
  7. Jiwei Li

    College of Computer Science and Technology, Zhejiang University, Hangzhou, China
    Competing interests
    The authors declare that no competing interests exist.
  8. Tao Xue

    Peking University, Beijing, China
    For correspondence
    txue@hsc.pku.edu.cn
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7045-2307

Funding

PKU-Baidu Fund (2020BD031)

  • Tao Xue

Fundamental Research Funds for the Central Universities (BMU2021YJ042)

  • Tao Xue

CAMS Innovation Fund for Medical Sciences (2017-I2M-1-004)

  • Tianjia Guan

Energy Foundation

  • Tao Xue

National Natural Science Foundation of China (4217050142)

  • Tao Xue

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: Procedures and questionnaires for standard DHS surveys have been reviewed and approved by ICF Institutional Review Board. All analyses are based on the open-accessed DHS data. The research plan has been approved by DHS, and all analyses adhere the guideline of data usage from DHS.

Reviewing Editor

  1. Eduardo Franco, McGill University, Canada

Publication history

  1. Received: April 10, 2021
  2. Accepted: September 26, 2021
  3. Accepted Manuscript published: September 29, 2021 (version 1)

Copyright

© 2021, Li et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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Further reading

    1. Epidemiology and Global Health
    2. Microbiology and Infectious Disease
    Paul Z Chen et al.
    Research Advance Updated

    Background:

    Previously, we conducted a systematic review and analyzed the respiratory kinetics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Chen et al., 2021). How age, sex, and coronavirus disease 2019 (COVID-19) severity interplay to influence the shedding dynamics of SARS-CoV-2, however, remains poorly understood.

    Methods:

    We updated our systematic dataset, collected individual case characteristics, and conducted stratified analyses of SARS-CoV-2 shedding dynamics in the upper (URT) and lower respiratory tract (LRT) across COVID-19 severity, sex, and age groups (aged 0–17 years, 18–59 years, and 60 years or older).

    Results:

    The systematic dataset included 1266 adults and 136 children with COVID-19. Our analyses indicated that high, persistent LRT shedding of SARS-CoV-2 characterized severe COVID-19 in adults. Severe cases tended to show slightly higher URT shedding post-symptom onset, but similar rates of viral clearance, when compared to nonsevere infections. After stratifying for disease severity, sex and age (including child vs. adult) were not predictive of respiratory shedding. The estimated accuracy for using LRT shedding as a prognostic indicator for COVID-19 severity was up to 81%, whereas it was up to 65% for URT shedding.

    Conclusions:

    Virological factors, especially in the LRT, facilitate the pathogenesis of severe COVID-19. Disease severity, rather than sex or age, predicts SARS-CoV-2 kinetics. LRT viral load may prognosticate COVID-19 severity in patients before the timing of deterioration and should do so more accurately than URT viral load.

    Funding:

    Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant, NSERC Senior Industrial Research Chair, and the Toronto COVID-19 Action Fund.

    1. Epidemiology and Global Health
    Audrie Lin et al.
    Research Advance Updated

    Background:

    Previously, we demonstrated that a water, sanitation, handwashing, and nutritional intervention improved linear growth and was unexpectedly associated with shortened childhood telomere length (TL) (Lin et al., 2017). Here, we assessed the association between TL and growth.

    Methods:

    We measured relative TL in whole blood from 713 children. We reported differences between the 10th percentile and 90th percentile of TL or change in TL distribution using generalized additive models, adjusted for potential confounders.

    Results:

    In cross-sectional analyses, long TL was associated with a higher length-for-age Z score at age 1 year (0.23 SD adjusted difference in length-for-age Z score [95% CI 0.05, 0.42; FDR-corrected p-value = 0.01]). TL was not associated with other outcomes.

    Conclusions:

    Consistent with the metabolic telomere attrition hypothesis, our previous trial findings support an adaptive role for telomere attrition, whereby active TL regulation is employed as a strategy to address ‘emergency states’ with increased energy requirements such as rapid growth during the first year of life. Although short periods of active telomere attrition may be essential to promote growth, this study suggests that a longer overall initial TL setting in the first 2 years of life could signal increased resilience against future telomere erosion events and healthy growth trajectories.

    Funding:

    Funded by the Bill and Melinda Gates Foundation.

    Clinical trial number:

    NCT01590095