Haemolytic Disease of the Newborn (HDN)

You, Your Baby and the RhD Factor

Everybody’s different.

And that goes for our blood as well. But, broadly speaking, everybody’s blood falls into a number of categories, or blood groups as they are called. Indeed, you may have already heard of the four main blood groups: Group A, Group O, Group B, Group AB which are carried on the red blood cells. Red blood cells are the commonest cells in the blood system and their job is to carry the oxygen you breathe around your body.

Usually when a mother and her baby belong to a different one of these blood groups, there is no problem. However, sometimes the mother and baby’s blood differ in a more important way. This difference is known as the Rhesus Factor, particularly the RhD Factor.

The RhD Factor is the name given to a special protein attached to the red blood cells in the blood. About 85% of people have the RhD Factor, the other 15% do not. People whose red blood cells carry the Factor are called ‘RhD-Positive’, those without are called ‘RhD-Negative’.

Below is an image of two red blood cells, one with the RhD Factor and one without

Please contact your GP or Midwife, for further information about the RhD Factor and what it means to you.