Objective: Previous research has reported associations between Helicobacter pylori and hyperemesis gravidarum (hyperemesis). Whether the human gastrointestinal microbiota is associated with hyperemesis has not been studied. The aim of the present study was to explore gut microbiota among women with and without hyperemesis. In addition, we also studied the consequence of the absence or presence of H. pylori on the metagenomics of intestinal microbiota.

Patients and Methods: Faecal samples were collected from immigrant pregnant women in Norway hospitalized due to hyperemesis (n=52) and pregnant women without hyperemesis (n=161). DNA extraction, 16S rRNA gene amplification and sequencing, and H. pylori PCR were conducted. Data on maternal age, parity, number of pregnancies, or patient history regarding hyperemesis was registered. Furthermore, information on country of birth and length of stay in Norway was also recorded. Additionally, use of antibiotics during the last 2 months before inclusion in the study was registered.

Results: Results from the H. pylori specific PCR demonstrated a lower carriage rate among pregnant women without hyperemesis (23.5%) compared to the hyperemesis-positive group (26.9%). However, the difference between the two groups was not significant (p>0.05). Faeces from hyperemesis-negative women were comprised of the following groups of bacteria (N=9): Actinobacteria (2 groups), Bifidobacteriales, Bifidobacteriaeae, Bifidobacterium, Bulleidia, Clostridiacae, Clostridiae div, and Unclassified Clostridiaceae. A higher number of groups (N=20) was detected in faeces from hyperemesis patients (viz., Alcaligenacae, Bacterioidaceae, Bacterioides, Betaproteobacteria, Burkholderidales, Clostridia, Clostridiales other types, Firmicutes, Ocillospira other types, Parabacteroides, Porphyromonadaceae, Rikenellaceae, Rikenellaceae other types, Ruminococcacae, Ruminococcacae, Ruminococcaceae other types, Ruminococcus, Sutterella, unclassified Lachnospiraceae, and unclassified Rikenellaceae).

Conclusions: In hyperemesis-positive women, gut microbiota displayed higher alpha diversity than hyperemesis-negative women (p=0.0015). Clostridiales were present in women with and without hyperemesis. However, more groups were observed in the hyperemesis group (viz., Bacteriodaceae, Bacteroides, Firmicutes, Clostridia and Betaproteobacteria).