Why doesn’t Mother Reject Fetus?The Immunological Concept of Pregnancy

The role of the immune system at the implantation site plays important role not rejecting fetus. Over fifty years ago, Sir Peter Medawar proposed the paradigm of why the fetus, as a semi-allograft, is not rejected by the maternal immune system. The presence of the maternal immune system at the implantation site was used as evidence to support this. Medawar's observation was based on the assumption that the placenta is an allograft expressing paternal proteins and, therefore, under normal immunological conditions, should be rejected. It is seen that the placenta is more than a transplanted organ. Based on the data discussed, there may be an active mechanism preventing a maternal immune response against paternal antigens. The trophoblast and the maternal immune system have evolved and established a cooperative status, helping each other for the success of the pregnancy. The differentiation and function of immune cells infiltrating the implantation site depends, largely on the microenvironment created by the placenta. This hypothesis is supported by trophoblast cells is able to induce monocyte-like THP-1 cells to secrete cytokines such as IL-6, IL-8, MCP-1, and GRO-α which has beneficial effects on trophoblast development and function.

The concept that pregnancy is associated with immune suppression has created a myth of pregnancy as a state of immunological weakness and, therefore, of increased susceptibility to infectious diseases. A challenging question is whether the maternal immune system is a friend or a foe of pregnancy. In this review, I discuss data associated to the role of the immune system during pregnancy and clinical implications. A new paradigm in terms of the fetal-maternal immune interaction as well as the immunological response of the mother to microorganism. Here the challenge for midwifery nurses is to better understand the immunology of pregnancy in order to deliver the appropriate treatment to patients with pregnancy complications as well as to evaluate many of the 'classical concepts' to define new approaches for a better understanding of the immunology of pregnancy that will benefit mothers and fetuses in different clinical scenarios. Always Nurse is a unique position to help clients by extending her role through updating new knowledge's and skills in all fields of health care system .So Immunological concept of pregnancy and its clinical implications could be an area of interest for midwifery nurses for clinical practice.