False pregnancy False pregnancy False pregnancy, also known as phantom, hysterical pregnancy, pregnancy scares or pseudocyesis, is the appearance of clinical or subclinical signs and symptoms associated with pregnancy when the person is not actually pregnant. False pregnancy may sometimes be purely psychological. It is generally believed that false pregnancy is caused by changes in the endocrine system of the body, leading to the secretion of hormones that cause physical changes similar to those during pregnancy. Some men experience the same illnesses as a woman would experience while pregnant when their partner is pregnant (see Couvade syndrome), possibly caused by pheromones that
Immune tolerance in pregnancy Immune tolerance in pregnancy Immune tolerance in pregnancy or gestational/maternal immune tolerance is the absence of a maternal immune response against (in other words, immune tolerance towards) the fetus and placenta during pregnancy, which thus may be viewed as unusually successful allografts, since they genetically differ from the mother. In the same way, many cases of spontaneous abortion may be described in the same way as maternal transplant rejection. It is studied within the field of reproductive immunology. The placenta functions as an immunological barrier between the mother and the fetus, creating an immunologically privileged site. For this purpose, it