[1] The latter typically only occurs in mothers of blood group O, because they can produce enough IgG antibodies to cause hemolysis.
[citation needed] Although very uncommon, cases of ABO HDN have been reported in infants born to mothers with blood groups A[2][3] and B.
[citation needed] However, ABO HDN is generally mild and short-lived and only occasionally severe because: Routine antenatal antibody screening blood tests (indirect Coombs test) do not screen for ABO HDN.
[citation needed] Diagnosis is usually made by investigation of a newborn baby who has developed jaundice during the first week of life.
If the bilirubin level is sufficiently high as to cause worry, it can be lowered via phototherapy in the first instance or an exchange transfusion if severely elevated.