Why Doesn’t a Mother Reject a Genetically Different Fetus?

Many basic multicellular organisms possess some form of immune response to protect themselves against the invasion of foreign objects. It was not until British scientist, Peter Medawar proposed a fundamental question that changed the way researchers studied the maternofetal relationship. A fetus, being genetically different from its mother should be rejected by the maternal immune system, however, it is not. Researchers have since discovered and developed several mechanisms that aim to explain how the maternal immune system prevents fetal rejection. The formation of a mechanical barrier, general and local suppression of the maternal immune system, and a shift in cytokine concentration during pregnancy have been suggested as reasons. Forthcoming discoveries in the field of reproductive immunology may further one’s understanding of immune regulation during pregnancy, in addition to other applications, such as, the immune responses regarding organ transplants. Although the proposed mechanisms mentioned above helped improve the understanding of how fetal rejection is avoided, many scientists concur that additional research is required to adequately explain the prevention of fetal rejection