Helicobacter pylori infection and severe hyperemesis gravidarum among immigrant women in Norway: a case–control study

Abstract

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. 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. 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. 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.