Modification of caesarean section on the associations between air pollution and childhood asthma in seven Chinese cities

Hongyao Yu, Yuming Guo, Xiaoyun Zeng, Meng Gao, Bo Yi Yang, Li Wen Hu, Yunjiang Yu, Guang Hui Dong*, Yang Zhou, Zhengmin Qian, Jia Sun, Stephen Edward McMillin, Michael S. Bloom, Joachim Heinrich, Iana Markevych, Lidia Morawska, Shyamali C. Dharmage, Bin Jalaludin, Luke Knibbs, Shao LinPasi Jalava, Marjut Roponen, Ari Leskinen, Mika Komppula, Y. I.M. Hung-Lam Steve, Ru Qing Liu, Xiao Wen Zeng, Seven Northeastern Cities Study group

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

3 Citations (Scopus)


It is unknown whether giving birth via caesarean section (c-section) is a modifier for the association between air pollution and asthma. From 2012 to 2013, 59,754 children between the ages of 2 and 17 were randomly selected from 94 middle schools, elementary schools and kindergartens in seven Chinese cities for a cross-sectional study. The children's parents or guardians completed questionnaires, from which data on asthma as well as asthma-related symptoms were obtained. Participants' exposure to particles with an aerodynamic diameter ≤1.0 μm (PM1), ≤2.5 μm (PM2.5), and ≤10 μm (PM10) and exposure to nitrogen dioxide (NO2) were estimated using random forest models. We used mixed effects logistic regression models and added an interaction term between mode of delivery and ambient air pollution into the model to estimate effect modification from c-sections after appropriate adjustments for potential confounding variables. Among children delivered by c-section, the adjusted ORs for asthma and its symptoms per interquartile range (IQR) increase of PM1, PM2.5, PM10 and NO2 (1.20 95% CI: 1.07–1.34 to 2.04 95% CI: 1.87–2.24) were significantly higher than those of children delivered vaginally (1.05 95% CI: 0.92–1.19 to 1.33 95%CI: 1.21–1.47). The interactions between c-sections and ambient air pollution were statistically significant for all studied respiratory disorders, except current wheeze. Delivery via c-section may increase the risks of air pollution on asthma and its symptoms in Chinese children.

Original languageEnglish
Article number115443
JournalEnvironmental Pollution
Publication statusPublished - Dec 2020

Scopus Subject Areas

  • Toxicology
  • Pollution
  • Health, Toxicology and Mutagenesis

User-Defined Keywords

  • Air pollution
  • Asthma
  • Asthma-related symptom
  • Caesarean section
  • Effect modification


Dive into the research topics of 'Modification of caesarean section on the associations between air pollution and childhood asthma in seven Chinese cities'. Together they form a unique fingerprint.

Cite this