Outcome of consecutive pregnancies in a patient with Bombay (Oh) blood group

A young lady with a rare Bombay (Oh) blood group had two successive uneventful pregnancies. Her serum contained a potent high-titre anti-H and serological as well as chemiluminescence tests, suggesting that the antibody was haemolytic. Her husband was of the normal H status. Theoretically, both babies should have been positive for the H antigen and should have suffered from haemolytic disease of the newborn. This apparent conundrum could be owing to the weak expression of the H antigens on the infant red cells.