Important message from the Arizona Wellness Center for Women regarding coronavirus (COVID-19).

Telemedicine Appointments  Face Mask Recommendations
Office Visits and Patient Safety
Request an Appointment

Obstetrical Services


The Rh Factor


Rh Factor*

During pregnancy, you will have a blood test to find your blood type. If your blook lacks the Rh antigen, it is called Rh Negative. If it has the antigen it is called Rh Positive. Problems can arise when the fetus' blood has the Rh factor and mother's blood does not.

The Rh Factor causes problems when a Rh-negative person's blood comes in contact with Rh-positive blood. If this occurs, the person with Rh-negative blood may become sensitized. This means he/she produces antibodies to fight the Rh factor as if it were a harmful substance. For example, an Rh-negative woman can become sensitized if she is pregnant with an Rh-positive fetus.

During pregnancy, mother and fetus do not share bood systems, but blood from the fetus can cross the placenta into the mother's system. When this occurs, a small number of pregnant women with Rh-negative blood who carry an Rh-positive fetus will react as though it were allergic to the fetal blood. Then, they become senstized by making antibodies which can go back to the fetus and attack fetal blood causing RBC breakdown and anemia, called hemolysis. It can become severe enough to cause serious illness, brain damage, or even death in the fetus or newborn.

Sensitization can occur any time the fetus' blood mixes with the mother's blood. It can occur if an Rh-negative woman has once had a miscarriage, induced abortion, ectopic prenancy or even a blood transfusion.

How can problems be prevented?

A simple blood test to determine your blood type and Rh factor and whether or not you have developed antibodeis to Rh-positive blood will be done during your first pregnancy visit. Hemoltic disease can be prevented if the Rh-negative woman has not made antibodies against the Rh factor. Rh Immunoglobulin (Rhlg) is a blood product that can prevent sensitization in almost all cases. It keeps her body from being able to respond to Rh-positive cells. However if the mother is already sensitized then the Rhlg is not useful.

If a woman is Rh-negative and has not been sensitized, her doctor may suggest that she receive Rhlg around 28 weeks or pregnancy to prevent sensitization during the last 3 months. Shortly after birth, if the child has Rh-positive blood, the mother should receive another does of Phlg. Each pregnancy and delivery of an Ph-positive child requires repeat doses of Rhlg in the Rh-negative mother.

Rh-negative women should also receive treatment after any miscarriage, ectopic pregnancy, or induced abortion. If you have further questions please direct them to your health care provider!

*All information was provided from ACOG

Click here for more information. (American College of Obstetricians and Gynecologists)