Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Rh and ABO
Name: Pamela C.
Status: Student
Age: 30s
Location: N/A
Country: N/A
Date: 2002

I am Rh negative, and my husband is Rh positive, so when I became pregnant, I became interested in Rh incompatibility. Neither my obstetrician nor any of the medical books or hematology web sites I have looked at could answer the following: Why is ABO incompatibility less serious than Rh incompatibility? They are both just proteins on red blood cells that you can develop antibodies to, right? So why are the results of incompatibility so different? It is fine to give a technical answer.

I am a registered Medical Technologist and I got out my Immunohematology text (blood banking). I could find no real good answer either. There were some hints, however. You probably know that the first child born to an Rh- mom and Rh+ dad usually shows no symptoms because the baby's blood cells are what is causing the mom to form antibodies. This usually does not happen until birth, when the placenta detaches and the mom's and baby's cells can mix. If you get anti-immune globulin ("the shot") within so many hours after birth this can find the baby's cells and inactivate them before your body knows they were there.

If this does not happen and you make antibodies to the baby's blood, your second child could be affected. You probably also know that if your husband is heterozygous (Rh+/Rh-) there is a 50% chance that each baby will be negative also. As far as why Rh is worse than ABO, what is your blood type? If you are type O, you have both anti-A and anti-B antibodies and there could be a reaction if the baby's cells mix with yours. There is also a possibility of ABO incompatibility between you and a child if you are, say, A and the baby is B. It does cause a mild hemolytic anemia in the baby, but I am told that a few days under the bilirubin lights usually takes care of this. Sorry I could not be of more help.


Click here to return to the Molecular Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory