Review: The Effect of In Utero Exposure to Maternal Inflammatory Bowel Disease and Immunomodulators on Infant Immune System Development and Function

Autoimmune and inflammatory disorders, including inflammatory bowel disease (IBD), commonly affect women of childbearing age, warranting the use of immunomodulatory agents at a time where pregnancy may be desired. In utero exposure to pro-inflammatory mediators from maternal IBD, IBD-associated intestinal dysbiosis, and immunomodulatory drug use may impact neonatal immune system development during what is considered to be a critical period, with potential long-lasting impacts on susceptibility to disease. Both the innate and adaptative immune systems of the neonatal differ to that of the adult in terms of both cellular composition and sensitivity to antigenic and innate stimulation. The infant immune system gradually develops to more closely resemble that of the adult. Exposure to maternal inflammation in utero may aberrantly impact this period of infant immune system development, with maternal autoimmune and inflammatory disorders shown to affect the physiologic changes in serum cytokine abundance observed during pregnancy. The maternal and neonatal intestinal microbiome greatly influence infant mucosal and peripheral immune system development, and thereby impact the susceptibility to short-term inflammatory diseases, the adequacy of vaccine response, and later life risk of atopic and inflammatory disorders. Maternal disease, mode of delivery, method of feeding, time of weaning to include solid foods in the diet, and neonatal antibiotic exposure all influence the composition of the infant microbiome, and thereby infant immune system maturation. How exposure to specific immunosuppressive medications in utero alters infant immune cell phenotype and response to stimulation has been explored, but with existing studies limited by the time at which samples are performed, heterogenicity in methods, and small sample size. Furthermore, the impact of more recently introduced biologic agents have not been explored. Evolving knowledge in this field may influence therapeutic preferences for individuals with IBD planning to conceive, particularly if substantive differences in the risk of infant infection and childhood immune disease are identified.