Mode of delivery and risk of asthma in children 5-14 years old in Tabriz, Iran

Introduction: It has been suggested that a cesarean section increases risk of developing asthma due to lack of exposure to maternal microflora during birth. To investigate the association between the mode of delivery and the risk of asthma in children aged 5-14 years in Tabriz, Iran. Methods: A case-control study was performed on 233 (case = 81, control = 152) children aged 5-14 years referred to outpatient clinics of Tabriz Children’s Hospital and Sheikhorrais Clinic in 2014. Clinical asthma diagnosis was done according to Global Initiative for Asthma Criteria. A questionnaire was administered to obtain a demographic, environmental, and clinical history. Age-sex frequency matching with cases was carried out during sampling for controlling of possible cofounding effects of age and sex for asthma. Results: Of 233 children, 53.6% of them were male (case group = 54.3% and control group = 53.3%). Over half (54.5%), the participants had been delivered by caesarian section. Cases were not significantly more likely to have been delivered by caesarian section as compared to controls [adjusted odds ratio (AOR) = 0.69; 95% confidence interval (CI) = 0.34-1.42]. However, more frequent episodes of common cold [b = 0.094; standard error (SE) (b) = 0.031, P < 0.001], birth order (second born children compared to firstborns) (AOR = 2.54; 95% CI = 1.18-5.46), high maternal education levels: 12 years (AOR = 3.76; 95% CI = 1.10-12.9), collegiate (AOR = 6.12; 95% CI = 1.43-26.20), and intra-family marriage (AOR = 2.89; 95% CI = 1.21-6.89) were associated with childhood asthma. Conclusion: Delivery mode was not associated with risk of developing childhood asthma in our study. Intra-family marriage increased the odds of childhood asthma. Further study on the relationship between maternal education and the odds of asthma is proposed.