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Maternal smoking around birth and respiratory tract infection in adult offspring: A Mendelian randomization study
Huan Ma1, Yuanyuan Li2,3, Hang Liang1
1Institute of Medicine, Chongqing College of Humanities Science and Technology, Chongqing, China.
Introduction:
Maternal smoking during pregnancy impairs lung immune responses and leads to a higher frequency of respiratory infection in children. This study aims to assess the association of maternal smoking around birth with respiratory tract infection in adult offspring, using Mendelian randomization (MR).
Methods:
This is an MR study based on the Integrative Epidemiology Unit (IEU) open Genome-Wide Association Study (GWAS) data. The exposure was maternal smoking around birth; the outcomes were upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), coronavirus disease 2019 (COVID-19), acute bronchitis, pneumonia, bacterial pneumonia, viral pneumonia, influenza pneumonia, and pneumonia death. The inverse variance weighted, weighted median, and MR-Egger methods were used as the main methods of MR analysis. Heterogeneity and pleiotropic analysis were performed to ensure the accuracy of the results.
Results:
After removing single-nucleotide polymorphisms (SNPs) related to smoking by the offspring, maternal smoking around birth was associated with an increased risk of LRTI (OR=2.68; 95% CI: 1.29-5.58; p=0.008), COVID-19 (OR=2.32; 95% CI: 1.30-4.14; p=0.004), acute bronchitis (OR=7.14; 95% CI: 2.54-20.06; p<0.001), pneumonia (OR=1.90; 95% CI: 1.07-3.38; p=0.030), and bacterial pneumonia (OR=2.96; 95% CI: 1.14-7.69; p=0.026). No significant correlation was detected between maternal smoking and URTI (OR=4.29; 95% CI: 0.72-25.68; p=0.111).
Conclusions:
This Mendelian randomization study provides evidence that maternal smoking around birth is associated with an increased risk of LRTIs, particularly acute bronchitis, pneumonia, and bacterial pneumonia, along with COVID-19, in adult offspring. These findings suggest that the detrimental impact of early-life tobacco smoke exposure on respiratory health persists into adulthood, likely mediated by long-term alterations in pulmonary development and immune system programming.
