Now, it turns out that we also have a natural way to obtain passive immunity and this takes place in a woman when a woman is pregnant with a child. So passive immunity can also be developed naturally. Pregnant women give their developing fetus passive immunity by producing specific antibodies known as immunoglobulin g. And immunoglobulins g are small enough to actually pass across the placental membrane and into the blood found inside our fetus. And what that gives the fetus is passive immunity to any type of antigen or pathogen that might infect that fetus. And this is important because as the fetus is developing his or her immune system is also developing. So it's important that during this process of development our fetus has an ability to fight off an infection that infects that mother.