Immunology and the immunological response to pregnancy.

The immune system in humans is a complex system capable of discriminating self from non-self, and mounting appropriate allogenic immune responses to protect themselves from foreign organisms. This system is made up of two arms of defense: the first one is a non-specific arm (innate), in which humans are born with and do not require antigenic recognition. The second one is specific arm (humoral) involving B and T cells that are capable of mounting responses to particular antigen with immense specificity. Both of these systems importantly interact with each other to protect humans in the most effective and efficient manner. Defects or malfunctions in these systems can result in a variety of illnesses and conditions. The immunology of pregnancy is a very unique, highly controlled system, which allows for survival of a fetus (semi-allograft), whilst simultaneously protecting a pregnant woman. There are immune shifts in pregnancy, which are well established to facilitate maternal-fetal tolerance. This promotes the concept that the immune system is not suppressed, but instead modulated to facilitate a pregnancy and explain the differential response to various pathogens in pregnancy. During pregnancy, the development of a fetal immunological system also occurs with intricate interaction between the maternal and fetal interface. The mechanism is preterm and term birth is poorly understood, but the immunological response has been well documented for both the pathological and physiological scenarios.