CD40LG and neonatal jaundice: This might be due to the fact that the mother is Rh-negative and the fetus is Rh-positive, and some fetal RBCs cross the placenta and enter the maternal circulation through a minor tear or at the time of delivery; fetal red cells sensitize the mother to antigens on the surface of the fetal red cells, causing the synthesis of anti-D, IgM, and IgG antibodies, leading to neonatal jaundice (22).