So let's assume for the time being that the fetus that is produced is actually R H positive. And that means that inside the fetus, inside the blood of the fetus the fetus will have red blood cells that contain the antigen D on the membrane of those red blood cells. The question is how will this actually affect that pregnancy and how will it affect any future pregnancy that the woman may have? So to answer this question, let's begin with the following diagram. So this is our fetus. This is the placenta that connects the bloodstream of the fetus to the bloodstream of our female, of the mother.