In rhesus disease, antibodies from a pregnant woman's blood attack her growing baby's blood cells. This does not harm the mum, but can be a serious risk to a baby.
Doctors may also call this condition haemolytic disease of the foetus and newborn (HDFN).
The risk of rhesus disease is usually picked up during routine antenatal screening. It occurs when the mum has rhesus negative blood (RhD negative), but her baby in her womb has rhesus positive blood (RhD positive).
Most people are RhD positive, with blood types determined by genes inherited from your parents.
The condition can usually be prevented with anti-D immunoglobulin injections.
However, these injections don't work if the mum has already been sensitised to RhD positive blood. In these cases, extra monitoring will be arranged during the pregnancy and during delivery. If a baby is born with rhesus disease, they may have jaundice or anaemia.
Treatment for rhesus disease after delivery includes phototherapy (light therapy), blood transfusions and intravenous immunoglobulin injections.