Rhesus (Rh) factor is an inherited protein found on the surface of red blood cells. If your blood has the protein, you're Rh positive. If your blood lacks the protein, you're Rh negative.

How do you know your rhesus?

One of these tests is to find out your blood group (A, B, AB or O) and your rhesus status (positive or negative) (NCCWCH 2008, NHS 2018). Your rhesus status is fixed by your genes: If you're rhesus positive (RhD positive), it means that a protein (D antigen) is found on the surface of your red blood cells.

How do I know if I am rhesus negative?

The Rh factor is a protein that can be found on the surface of red blood cells. If your blood cells have this protein, you are Rh positive. If your blood cells do not have this protein, you are Rh negative.