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 …

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 …

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 …

Dec 18, 2025 · Rh blood group system, system for classifying blood groups according to the presence or absence of the Rh antigen, often called the Rh factor, on the cell membranes of …

This patient FAQ provides information on the Rh factor and what it means for pregnancy.

Jun 27, 2023 · 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 …

Rh incompatibility is when the blood of a fetus has a protein called Rh factor and the mother’s blood doesn’t. This can cause anemia, making a baby’s level of red blood cells very low. …

Jul 25, 2025 · The Rhesus (Rh) factor is a protein found on the surface of red blood cells. Its presence or absence classifies an individual’s blood as either Rh-positive or Rh-negative. This …

Aug 8, 2024 · What Is Rh Factor? The Rh factor is a type of protein that's usually found on red blood cells. When you have this protein, you’re considered Rh positive. About 85% of people …

The Rh factor, also known as the Rhesus factor, is a specific protein found on the surface of red blood cells (RBCs). Individuals who possess this protein are classified as Rh-positive (Rh+), …