title: Helicobacter pylori infection and severe hyperemesis gravidarum among immigrant women in Norway: a case-control study.
abstract: OBJECTIVE
  To study associations between Helicobacter pylori exposure and severe hyperemesis gravidarum (HG) among immigrant women in Norway by exploring IgG seropositivity and H. pylori antigens in faeces. Additionally, we investigated whether cytotoxin-associated gene A product (CagA) and vacuolating cytotoxin A (VacA) seropositivity modulated this association.
  
  
  METHODS
  An institution-based case-control study among immigrant women in Norway was performed at Ullevål and Akershus University Hospitals in September 2005-December 2007. Blood samples were used to explore IgG, CagA and VacA seropositivity, and faecal samples were used to explore the presence of antigens. Multiple logistic regressions were used to study associations between HG and H. pylori exposure.
  
  
  RESULTS
  The sample comprised 170 women: 62 cases and 108 controls. The observed proportion of IgG seropositive women did not differ between cases and controls. Neither IgG seropositivity nor CagA and VacA seropositivity were significantly associated with HG. For IgG positive and CagA and VacA negative women, the crude OR was 1.26 (95% CI: 0.57-2.82). For those being IgG positive and CagA and VacA positive, the crude OR was 0.82 (0.40-1.68). Adjustment for confounding factors, such as maternal age, body mass index and earlier HG, did not change the results. Additional adjustment for faecal antigens did not change the conclusions regarding these associations. Likewise, the crude OR for H. pylori antigens was not statistically significant. Adjustment for confounders and IgG seropositivity did not change this result.
  
  
  CONCLUSIONS
  This study did not find H. pylori exposure to be significantly associated with severe HG among immigrant women in Norway. This was regardless of whether H. pylori exposure was investigated by IgG seropositivity, CagA and VacA seropositivity or by the presence of H. pylori antigens in faeces. These results may indicate that the association between H. pylori and HG is weaker than previously expected, particularly in populations with high prevalence of H. pylori infection.
authors.affiliation: Department for Genes and Environment, Division for Epidemiology, Norwegian Institute of Public Health, Oslo, Norway. ase.vigdis.vikanes@fhi.no
authors.forename: Ase V
authors.initials: AV
authors.lastname: Vikanes
authors.forename: Nathalie C
authors.initials: NC
authors.lastname: Støer
authors.forename: Nina
authors.initials: N
authors.lastname: Gunnes
authors.forename: Andrej M
authors.initials: AM
authors.lastname: Grjibovski
authors.forename: Sven O
authors.initials: SO
authors.lastname: Samuelsen
authors.forename: Per
authors.initials: P
authors.lastname: Magnus
authors.forename: Kjetil K
authors.initials: KK
authors.lastname: Melby
mesh_terms: D000328:Adult; D000349:Africa / Q000208:ethnology; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology; D001208:Asia / Q000208:ethnology; D001426:Bacterial Proteins / Q000276:immunology; D016022:Case-Control Studies; D016001:Confidence Intervals; D005243:Feces; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis / Q000208:ethnology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D006939:Hyperemesis Gravidarum / Q000208:ethnology*; D007074:Immunoglobulin G / Q000097:blood; D016015:Logistic Models; D015999:Multivariate Analysis; D009664:Norway / Q000453:epidemiology; D016017:Odds Ratio; D011247:Pregnancy; D015995:Prevalence; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D007074:Immunoglobulin G; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori