Does maternal smoking hinder mother child transmission of Helicobacter pylori infection?

Evidence for early childhood as the critical period of Helicobacter pylori infection and for clustering of the infection within families suggests a major role of intrafamilial transmission. In a previous study, we found a strong inverse relation between maternal smoking and H, pylori infection among preschool children, suggesting the possibility that mother-child transmission of the infection may be less efficient if the mother smokes. To evaluate this hypothesis further, we carried out a subsequent population-based study in which H. pylori infection was measured by C-13-urea breath test in 947 preschool children and their mothers. We obtained detailed information on potential risk factors for infection, including maternal smoking, by standardized questionnaires. Overall, 9.8% (93 of 947) of the children and 34.7% (329 of 947) of the mothers were infected. Prevalence of infection was much lower among children of uninfected mothers (1.9%) than among children of infected mothers (24.7%). There was a strong inverse relation of children's infection with maternal smoking (adjusted odds ratio = 0.24; 95% confidence interval = 0.12-0.49) among children of infected mothers, but not among children of uninfected mothers. These results support the hypothesis of a predominant role for mother-child transmission of H. pylori infection, which may be less efficient if the mother smokes.