Do pregnancy-related changes in the microbiome stimulate innate immunity?

• Changes in the immune system and the host microbiome during pregnancy may positively influence the course of inflammatory bowel disease (IBD).
• Innate immunity defects leading to IBD may have been ‘repaired’ during pregnancy.
• The host may be able to control the intestinal microbiota and use it as a tool to support body functions.

Pregnancy has a beneficial influence on the course of certain autoimmune diseases such as inflammatory bowel disease (IBD). It was recently reported that during pregnancy the microbiome undergoes profound changes that are associated with host physiological and immunological adaptations. Here we propose that microbiome remodeling during pregnancy is an active response of the mother, possibly to alter immune system status, and to facilitate metabolic and immunological adaptations that are needed for a successful pregnancy. Furthermore, these changes in the microbiome may ensure the transfer of specific traits into the neonatal gut. As the underlying mechanisms are not well understood, elucidating how pregnancy-related changes in the microbiome influence IBD would be of obvious value for designing rational therapy.