title: Time trends in allergic sensitisation and Helicobacter pylori prevalence in Finnish pregnant women.
abstract: BACKGROUND
  An increase in the prevalence of allergic conditions has been documented in Finland, correlating with the diminishing prevalence of Helicobacter pylori infections. We investigated whether the increase of allergic sensitisation still continues and correlates with the prevalence of H. pylori infections.
  
  
  METHODS
  The sera from 958 pregnant women in 1983, 1989, 1995 and 2001 were analysed for the presence of antibodies against H. pylori. In addition, allergen-specific IgE antibodies and total levels of IgE antibodies were measured.
  
  
  RESULTS
  A clear birth cohort effect was found in the prevalence of allergic sensitization: allergen-specific IgE was more frequent among recent birth cohorts than earlier ones (p = 0.001). The frequency of H. pylori antibodies followed the opposite trend (p < 0.001) and the increase in allergic sensitisation was only seen among H. pylori-negative women. A modest increase was also seen in allergic sensitisation between the 4 time series among the H. pylori-negative subjects (p = 0.04). Total IgE levels did not differ between birth cohorts or time series.
  
  
  CONCLUSIONS
  The results suggest that hygiene-related environmental factors have played a role in the increase of allergic sensitisation during the last decades.
authors.affiliation: Department of Virology, University of Tampere, Tampere, Finland. tapio.seiskari@uta.fi
authors.forename: Tapio
authors.initials: T
authors.lastname: Seiskari
authors.forename: Hanna
authors.initials: H
authors.lastname: Viskari
authors.forename: Minna
authors.initials: M
authors.lastname: Kaila
authors.forename: Anna-Maija
authors.initials: AM
authors.lastname: Haapala
authors.forename: Pentti
authors.initials: P
authors.lastname: Koskela
authors.forename: Heikki
authors.initials: H
authors.lastname: Hyöty