PREGNANCY IS CHARACTERIZED BY MICROBIAL, INFLAMMATORY AND METABOLIC ALTERATIONS

It is well known that the microbiome, the collection of all bacteria in and our bodies, influence metabolism, immunity and even behavior. As this research field is still in infancy, the mechanisms by which these bacteria affect specific host characteristics are still largely unknowns.

Pregnancy is a remarkable biological process in which the female body undergoes hormonal, as well as immunological and metabolic changes to support fetal growth and development. During this period the levels of hormones secreted by the corpus luteum and placenta rise dramatically, there are changes in the immune system, and the pregnant female gains weight. All these changes must be synchronized in order to maintain the health of the mother and of the offspring. The endocrine changes in pregnancy, especially the rise in progesterone and estrogen levels, alter the immune system and immune response. Another change during pregnancy occurs in the gut microbial composition. It has been shown that in the first trimester of pregnancy, gut microbiota composition is similar to that of healthy non- pregnant control women, while from the first to the third trimester of pregnancy, gut microbiota composition changes dramatically and is characterized by increased levels of Proteobacteria and Actinobacteria. In addition, beta diversity (between subject) increases in the third trimester, while the bacterial richness (α- diversity) is significantly decreased.

In this study we address the changes in gut microbiota composition and markers of inflammation in pregnant and pseudopregnant mice. We further show that the changes in gut microbiota occur during late pregnancy, and describe a correlation between physical parameters of the host and bacterial composition. We also found differences in cecal metabolomics profile of pregnant mice.