Summary
Increasing evidence suggests that immune system development begins in utero and is heavily influenced by the maternal immune status during gestation (1). Pregnancy is associated with suppression of the maternal immune system to promote the growth of the allogeneic fetus, albeit at the cost of increased susceptibility to infection (2). Mild maternal infections—such as mild urinary tract, skin, and respiratory tract infections—are often self-resolved and underdiagnosed. It remains poorly understood whether transient maternal inflammation induced by a mild infection leaves an immunologic scar in offspring. On page 982 of this issue, Lim et al. (3) tackle this question in mice and find that the cytokine interleukin-6 (IL-6), induced by a mild maternal infection, causes epigenetic imprinting of fetal intestine that has a long-term impact on immune responses to enteric pathogens and tissue inflammation in adulthood.