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

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. Preprint posted: April 30, 2021 (view preprint)
  3. Accepted: September 26, 2021
  4. Accepted Manuscript published: September 29, 2021 (version 1)
  5. Version of Record published: November 2, 2021 (version 2)

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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  1. Jiajianghui Li
  2. Tianjia Guan
  3. Qian Guo
  4. Guannan Geng
  5. Huiyu Wang
  6. Fuyu Guo
  7. Jiwei Li
  8. Tao Xue
(2021)
Exposure to landscape fire smoke reduced birthweight in low- and middle-income countries: findings from a siblings-matched case-control study
eLife 10:e69298.
https://doi.org/10.7554/eLife.69298
  1. Further reading

Further reading

    1. Epidemiology and Global Health
    2. Medicine
    Qing Shen, Huan Song ... Unnur Valdimarsdóttir
    Research Article Updated

    Background:

    The association between cardiovascular disease (CVD) and selected psychiatric disorders has frequently been suggested while the potential role of familial factors and comorbidities in such association has rarely been investigated.

    Methods:

    We identified 869,056 patients newly diagnosed with CVD from 1987 to 2016 in Sweden with no history of psychiatric disorders, and 910,178 full siblings of these patients as well as 10 individually age- and sex-matched unrelated population controls (N = 8,690,560). Adjusting for multiple comorbid conditions, we used flexible parametric models and Cox models to estimate the association of CVD with risk of all subsequent psychiatric disorders, comparing rates of first incident psychiatric disorder among CVD patients with rates among unaffected full siblings and population controls.

    Results:

    The median age at diagnosis was 60 years for patients with CVD and 59.2% were male. During up to 30 years of follow-up, the crude incidence rates of psychiatric disorder were 7.1, 4.6, and 4.0 per 1000 person-years for patients with CVD, their siblings and population controls. In the sibling comparison, we observed an increased risk of psychiatric disorder during the first year after CVD diagnosis (hazard ratio [HR], 2.74; 95% confidence interval [CI], 2.62–2.87) and thereafter (1.45; 95% CI, 1.42–1.48). Increased risks were observed for all types of psychiatric disorders and among all diagnoses of CVD. We observed similar associations in the population comparison. CVD patients who developed a comorbid psychiatric disorder during the first year after diagnosis were at elevated risk of subsequent CVD death compared to patients without such comorbidity (HR, 1.55; 95% CI, 1.44–1.67).

    Conclusions:

    Patients diagnosed with CVD are at an elevated risk for subsequent psychiatric disorders independent of shared familial factors and comorbid conditions. Comorbid psychiatric disorders in patients with CVD are associated with higher risk of cardiovascular mortality suggesting that surveillance and treatment of psychiatric comorbidities should be considered as an integral part of clinical management of newly diagnosed CVD patients.

    Funding:

    This work was supported by the EU Horizon 2020 Research and Innovation Action Grant (CoMorMent, grant no. 847776 to UV, PFS, and FF), Grant of Excellence, Icelandic Research Fund (grant no. 163362-051 to UV), ERC Consolidator Grant (StressGene, grant no. 726413 to UV), Swedish Research Council (grant no. D0886501 to PFS), and US NIMH R01 MH123724 (to PFS).

    1. Epidemiology and Global Health
    Bingyi Yang, Bernardo García-Carreras ... Derek A Cummings
    Research Article

    Background: Over a life-course, human adaptive immunity to antigenically mutable pathogens exhibits competitive and facilitative interactions. We hypothesize that such interactions may lead to cyclic dynamics in immune responses over a lifetime.

    Methods: To investigate the cyclic behavior, we analyzed hemagglutination inhibition titers against 21 historical influenza A(H3N2) strains spanning 47 years from a cohort in Guangzhou, China and applied Fourier spectrum analysis. To investigate possible biological mechanisms, we simulated individual antibody profiles encompassing known feedbacks and interactions due to generally recognized immunological mechanisms.

    Results: We demonstrated a long-term periodicity (about 24 years) in individual antibody responses. The reported cycles were robust to analytic and sampling approaches. Simulations suggested that individual-level cross-reaction between antigenically similar strains likely explain the reported cycle. We showed that the reported cycles are predictable at both individual and birth-cohort level and that cohorts show a diversity of phases of these cycles. Phase of cycle was associated with the risk of seroconversion to circulating strains, after accounting for age and pre-existing titers of the circulating strains.

    Conclusions: Our findings reveal the existence of long-term periodicities in individual antibody responses to A(H3N2). We hypothesize that these cycles are driven by pre-existing antibody responses blunting responses to antigenically similar pathogens (by preventing infection and/or robust antibody responses upon infection), leading to reductions in antigen specific responses over time until individual's increasing risk leads to an infection with an antigenically distant enough virus to generate a robust immune response. These findings could help disentangle cohort-effects from individual-level exposure histories, improve our understanding of observed heterogeneous antibody responses to immunizations, and inform targeted vaccine strategy.

    Funding: This study was supported by grants from the NIH R56AG048075 (D.A.T.C., J.L.), NIH R01AI114703 (D.A.T.C., B.Y.), the Wellcome Trust 200861/Z/16/Z (S.R.) and 200187/Z/15/Z (S.R.). This work was also supported by research grants from Guangdong Government HZQB-KCZYZ-2021014 and 2019B121205009 (Y.G. and H.Z.). D.A.T.C., J.M.R. and S.R. acknowledge support from the National Institutes of Health Fogarty Institute (R01TW0008246). J.M.R. acknowledges support from the Medical Research Council (MR/S004793/1) and the Engineering and Physical Sciences Research Council (EP/N014499/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.