The Rh factor is a protein that can be present on the surface of red blood cells. If a person has this protein, they are considered Rh-positive, while those who do not have it are Rh-negative. This classification is important in blood transfusions and pregnancy, as mismatched Rh types can lead to complications. During pregnancy, if an Rh-negative mother carries an Rh-positive baby, her body may produce antibodies against the baby's blood cells. This can cause a condition called hemolytic disease of the newborn, which can be serious. Medical interventions can help manage these risks effectively.