ABO antibodies are naturally occurring antibodies. The ABO antibodies found in the Group O individuals include anti-A and anti-B. In Group O individuals, it tends to be predominantly immunoglobulins G (IgG), although immunoglobulins M and IgA components are also present. Infants of Group O mothers are at higher risk for hemolytic disease of the fetus and new-born than those born to mothers with Group A or B because IgG readily cross the placenta. At the same time, abnormal high concentration of ABO antibody in mother can lead to destruction of platelets in neonates and leads to development of neonatal alloimmune thrombocytopenia as human platelets carry detectable quantities of A and B blood group antigens on their surface. Proper and early diagnosis combined with treatment with intravenous immunoglobulins or transfusion with compatible platelets, may be from mother, can save the neonate from bleeding episodes.