There are studies that found a higher prevalence of antibodies against Helicobacter pylori (Hp) in patients with hyperemesis gravidarum, compared to asymptomatic pregnant women. Objective. To determine the relationship between seropositivity to Hp and the presence of nausea and vomiting during the first 20 weeks of gestation in pregnant women of a hospital network, from March to December 2015. Material and methods. Unmatched case-control studies in pregnant women until 20 weeks of gestation. The Rhodes’ index for nausea and vomiting classified pregnant women in cases (9-40 points) and controls (8 points). Hp seropositivity was defined as IgG ≥ 1.1 U/mL. The association between Hp and nausea and vomiting of pregnancy was determined by logistic regression analysis controlling for age, parity, gestational age and socioeconomic status. Results. A total of 108 patients were included, 21 controls and 87 cases. There were no significant differences in age (p = 0.916), parity (p = 0.18) and socioeconomic status (p = 0.36). Hp seropositivity in cases was 78.2% (68/87) and controls 61.9% (13/21). In the logistic regression analysis, cases had higher risk of Hp seropositivity than controls (OR = 3.05; 95% CI: 0.92-10.1; p = 0.068), but was not significant. Conclusions. Patients with nausea and vomiting in the first 20 weeks of gestation had a higher risk of having been exposed to Hp, although this relationship was not significant due to the small sample size.