rhesus haemolytic anaemia

rhesus haemolytic anaemia (RHA)

a serious blood abnormality in newborn children in which LYSIS of red blood cells causes anaemia, the condition arising from a reaction between Rhesus antigens and antibodies (see RHESUS BLOOD GROUP). RHA occurs when a second (and subsequent) Rh-positive child is born to a Rh-negative mother. The mother is sensitized to the Rhesus factor in foetal blood cells transferred from the first baby at PARTURITION and produces rhesus antibodies in response. When she is pregnant again, her Rhesus antibodies pass to the foetus, resulting in RHA when the child is born. The condition can be prevented by the mother being given a large dose of rhesus antibodies immediately after the birth of her first child. These antibodies will destroy the foetal cells in her blood before she has time to become sensitized to them.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005