The disease course of autoimmune diseases such as rheumatoid arthritis is altered during pregnancy, and a similar
modulatory role of pregnancy on inflammatory bowel disease (IBD) has been proposed. Hormonal, immunological, and
microbial changes occurring during normal pregnancy may interact with the pathophysiology of IBD. IBD consists of
Crohn’s disease and ulcerative colitis, and because of genetic, immunological, and microbial differences between these
disease entities, they may react differently during pregnancy and should be described separately. This review will address
the pregnancy-induced physiological changes and their potential effect on the disease course of ulcerative colitis and
Crohn’s disease, with emphasis on the modulation of epithelial barrier function and immune profiles by pregnancy
hormones, microbial changes, and microchimerism