Metagenomic Analysis of Oral Microbiome during pregnancy

Abstract

Pregnancy is a dynamic physiological process associated with significant hormonal, immune and metabolic changes to support the growth and development of the fetus. Several studies have highlighted the role of gut microbiota during pregnancy1. The composition of gut microbiota changes dramatically during the course of pregnancy with an increase in Proteobacteria and Actinobacteria, a decline in butyrate-producing bacteria and a reduction in bacterial richness at the end of pregnancy2. These modifications were anticipated to favour the increased metabolic demand during pregnancy, which will, in turn, support healthy fetal growth3. Gut microbiota has also been suggested to contribute to weight gain during pregnancy via increased absorption of glucose and fatty acids, induction of catabolic pathways, increased fasting-induced adipocyte factor secretion, and stimulation of the immune system2, 4. The oral cavity houses the second most diverse microbiota after the gut harbouring over 700 species of bacteria. Oral microbiota plays a crucial role in maintaining oral homeostasis, protecting the oral cavity and preventing disease development5. Little is known about the role of the oral microbiome during pregnancy. One study examined changes in oral microbiota during pregnancy on Japanese women and found that the total viable microbial counts were higher during pregnancy, as were levels of the pathogenic bacteria Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Candida6. Several studies have also found correlations between oral infections and pregnancy complications, further suggesting mechanisms connecting the oral microbiome with the state of pregnancy7. The Qatari Birth Cohort (QbiC) was successfully developed in July 2018 by Qatar Biobank. It is an epidemiological study that aims to assess the synergetic role of environmental exposure and genetic factors in the development of chronic disease. It monitors the health of women throughout their pregnancy and after birth. The present study is designed to explore changes in the salivary microbiome, using high throughput sequencing during pregnancy and to explore key microbial clades involved in pregnancy.