WebMD
Font Size
A
A
A

Rh Incompatibility

People without Rh factor on the surface of their blood cells are Rh-negative and have Rh incompatibility with blood that is Rh-positive. This incompatibility means that when exposed to Rh-positive blood more than once, the immune systems of people with Rh-negative blood produce antibodies to destroy the Rh-positive blood cells.

Pregnancy and blood transfusions are the two most common ways that a person with Rh-negative blood can be exposed to Rh-positive blood.

In a woman with Rh-negative blood who has been exposed at least once to Rh factor (usually from a previous pregnancy), this immune system response can cause serious problems during a future pregnancy if the fetus has Rh-positive blood. The mother's immune system produces Rh antibodies that cross the placenta and attack the fetal blood cells. This can be prevented by giving the mother an injection of antibodies, called RhoGAM.

People requiring blood transfusions have Rh testing and are given only compatible blood.

By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer William Gilbert, MD - Maternal and Fetal Medicine
Last Revised October 20, 2011

WebMD Medical Reference from Healthwise

Last Updated: October 20, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.