Since the embryo does not grow in the womb as soon as a woman is born, the embryo during pregnancy is a foreign body, a [foreign body] that does not belong to her own body. A tenacious [foreign] body In the face of a foreign object, the body usually makes a protective response, which is called [immune response]. For example, when the body finds a virus invading, it will produce immune cells and immune factors to kill these foreign substances. Similarly, when the embryo [attempts to] colonize the uterus, it is a foreign substance to the mother. However, the specific mechanism by which the normal mother can tolerate and not reject the fetus is still unclear, which may be related Read More …