Postpartum Autoimmune Thyroid Syndrome: A Model of Aggravation of Autoimmune Disease

Postpartum thyroid dysfunction is rather a common problem during the postpartum period being found in approximately 5% of mothers in the general population. It occurs from subclinical autoimmune thyroiditis that is aggravated after parturition and causes various types of thyroid dysfunction. Immune activity is physiologically suppressed during pregnancy so that the fetus is not rejected, and rebounds above the normal level after parturition. Graves' disease and Hashimoto's thyroiditis also spontaneously ameliorate during pregnancy, and are often aggravated after parturition. The high-risk mothers for postpartum thyroid dysfunction are well screened by antithyroid microsomal antibody (MCAb) and 60% to 70% of MCAb-positive mothers develop postpartum thyroid dysfunction, which is transient in most cases. New onset of Graves' disease may be screened by thyroid-stimulating antibody (TSAb) and 70% of TSAb-positive mothers develop either transient or persistent postpartum Graves' disease that usually occurs 3 to 6 months postpartum. Immune rebound after parturition may cause not only autoimmune thyroid diseases but other autoimmune diseases, which may be investigated with similar strategies to those in postpartum autoimmune thyroid disease. Thus, we found that postpartum onset of rheumatoid arthritis was found in 0.08% of women in the general population and could be partially predicted by measuring rheumatoid factors in early pregnancy. There are several case reports of other autoimmune diseases that develop after delivery; postpartum renal failure or postdelivery hemolytic-uremic syndrome, postpartum idiopathic polymyositis, postpartum syndrome with antiphospholipid antibodies, postpartum autoimmune myocarditis. Many other possible postpartum autoimmune diseases are still unexplored. Puerperal diseases should be carefully examined in relation to autoimmune abnormalities in the affected organs.