Immunology of pregnancy

"Until the last decade, there was little a couple could do if they suffered from recurrent pregnancy losses. Miscarriages that couldn't be attributed to chromosomal defects, hormonal problems or abnormalities of the uterus were labeled "unexplained." New research, however, indicates that as many as 80 percent of "unexplained" losses may the attributable to immunological factors - and some new therapies are enabling up to 80 percent of those affected to carry a baby to term.

"The immune system functions as the first line of defense against disease. It works by identifying proteins as normal or foreign. The immune response to a foreign protein is to neutralize or destroy the antigen. An antigen is a protein marker on the surface of a cell that identifies the cell as "self" or "nonself" An antigen can cause the production of antibodies. Antibodies are complex compounds made by the white blood cells (WBCs) that combine with specific antigens to destroy or control bacterial infections. As bacteria enter the body, WBCs produce antibodies to provide protection against illness.

"The immunologic causes for pregnancy loss and implantation failure are the result of abnormalities in antibody responses. These responses fall into two categories: autoimmune and alloimmune.

"Contributions to a pregnancy represent the pairing of genes from both man and woman. Autoimmune represents the immunologic response of the mother to a pregnancy ("self-immune" problems). Autoimmune disorders that can cause rejection of a pregnancy mean the woman is rejecting her own proteins - in other words, treating them like they are an invading illness. Autoantibodies are antibodies which attack one's own antigens.

"Alloimmune problems indicate a mother's response to the man's genetic contribution to the pregnancy ("other-immune" problems). Alloimmune disorders are the rejection of a protein from the man. Both kinds of immune disorders can be determined with blood tests."

(Excerpts from: Immunology May Be Key To Pregnancy Loss by Carolyn B. Coulam M.D. and Nancy P. Hemenway, The InterNational Council on Infertility Information Dissemination, 2000.)