Immunological Changes During Pregnancy

Pregnancy is a physiological condition where the fetal allograft grows over 9 months in the mother without rejection. The immune system plays a key role in inducing tolerance to the fetus. The immune milieu is initially proinflammatory to help implantation and later changes to a tolerogenic type during most of the pregnancy to protect the fetus from rejection and then again becomes proinflammatory to help with the separation of placenta and delivery of the baby. Patients with autoimmune rheumatic diseases have pre-existing immunological abnormalities that can have an adverse impact on fetal development as well as on the immunological changes in pregnancy. Alternatively, tolerogenic milieu during pregnancy can sometimes lead to disease remission. Transplacental transfer of autoantibodies can have an adverse outcome for the fetus, such as the development of heart block in a mother with anti-Ro antibodies. Further, the use of immunosuppressive drugs can cause immunological changes in the growing fetus. Understanding of the immune pathways has opened new ways to improve fetal outcomes.