The Rhesus factor, or Rh factor, is a certain type of protein found on the outside of red blood cells. People are either Rh-positive (they have the protein) or Rh-negative (they don’t have the protein). …

The term "Rh" was originally an abbreviation of "Rhesus factor". It was discovered in 1939 by Karl Landsteiner and Alexander S. Wiener, who, at the time, believed it to be a similar antigen found in …

Apr 17, 2026 · The positive or negative sign next to the blood groups is known as the Rhesus (Rh) factor. The Rh factor is an inherited protein that can be found on the surface of the red blood cell.

Apr 30, 2025 · An Rh factor test is a basic blood test. The blood sample usually is taken during the first prenatal visit and sent to a lab for testing. No special preparation is necessary. If you're Rh positive, …

Mar 14, 2026 · The Rh factor is a protein found on the surface of red blood cells. If your red blood cells carry this protein, your blood type is Rh-positive (noted with a “+” after your ABO type, like A+ or O+).

Most people are Rh positive, meaning they have inherited the Rh factor from either their mother or father. If a fetus does not inherit the Rh factor from either the mother or father, then the fetus is Rh …

Apr 25, 2023 · The short answer is that Rh factor is very, very old. Like I mentioned earlier, Rh factor is short for Rhesus factor. This actually refers to how scientists first discovered Rh: in Rhesus macaque …

The “positive” or “negative” in your blood type refers to whether your red blood cells carry a specific protein called the Rh factor on their surface. If the protein is present, you’re Rh-positive (like A+ or …

Oct 11, 2021 · The rhesus factor, or Rh factor, is a protein that may be present on the surface of red blood cells (RBCs). If RBCs contain the Rh antigen, they are Rh-positive, and if not, they are Rh …

Nov 3, 2023 · In the same way that there are different major blood groups (type A, type B, type O), there is also what is called an “Rh Factor.” The Rh factor is an inherited protein found on the surface of …