rh

/ɑr eɪtʃ/
noun
  1. A protein found on the surface of red blood cells; the Rh factor is used to classify blood types as positive or negative.
    • Doctors check the Rh status of pregnant women to prevent complications.
    • If a mother is Rh negative and the baby is Rh positive, special treatment may be needed.
    • Her blood type is O negative, which means she lacks the Rh factor.