The gut microbiome and nausea in pregnancy

Sammanfattning: Nausea and vomiting are among the most common symptoms of early pregnancy. Its most extreme form Hyperemesis gravidarum often requires hospitalization and has been linked as a risk factor of perinatal depression. The emetic reflex is to a large extent triggered in the intestinal epithelium by the enterochromaffin cells, however the interplay between gut microbiome and pregnancy nausea is yet unclear. The aim of this study is to investigate the variation in gut microbiota diversity on second-trimester pregnant women with different levels of nausea, and to ascertain potential key species involved in that variation. Using shotgun sequencing to capture bacterial diversity from 1078 fecal samples, we found a reduction on species richness on women with strong nausea. There are measurable differences in the gut microbiota community composition based on the strength of nausea although depression seemed to be even more relevant to explain those differences. Our results provide evidence for the association of nausea and perinatal depression, but further studies are needed to elucidate the mechanisms underpinning the gut-brain axis cross-talk role in nausea and perinatal depression. No evidence of variation in species evenness or differential abundance of species were found. Finally, random forests results point at Lactococcus lactis as potentially displaying a key role determining the intensity of the nausea, although better models are needed to infer clear assumptions.