Prenatal Testing-Rh Factor

Posted on: March 8, 2021 | birth, Birth Work, Community, Pregnancy, Prenatal

This prenatal appointment brought on nervousness, just as much as it brought Claudia at ease. At 10 weeks pregnant, Claudia was beginning to find her footing with being pregnant. She found that if she kept rice cakes and water by the nightstand, she would have something in her belly before starting her day; and that made the baby happy. If she used her Palmer’s lotion, she wouldn’t gag, but her floral smelling lotions made her nauseous. What she wasn’t prepared for however, was finding out about Rh factor and that she was Rh-positive. 

What is Rh factor?

Rh factor is a protein that may be found on red blood cells. If your blood cells contain this protein, an individual is Rh positive. If an individual’s blood cells do not contain this protein, they are Rh negative. 

An Rh factor is inherited, and can be obtained from either the paternal or maternal gene. The gestational carrier may be positive, and the baby negative. Additionally, if the gestational carrier is negative but the baby is positive, that creates an Rh incompatibility.

If there’s an incompatibility found, the body will see the blood cells as foregin, and attack the blood cells of the baby. This could result in fetal demise. 

When is the test conducted?

An Rh factor antibodies test is conducted by a blood sample during your first prenatal visits. A screen can also be conducted to gauge if a Rh negative individual has made Rh-positive antibodies. 

If an individual’s test results in Rh-positive, a medication is administered to stop the body from making the antibodies. The shot Rh immunoglobulin (RhIg) is given at 28 weeks, and then again at the birth of a positive baby, within 72 hours.

What do the results mean?

Red blood cells carry oxygen through the blood to the entire body.  A positive Rh factor test can result in anemia where red blood cells are destroyed faster than they are regenerated. Therefore, the growing fetus is not receiving enough oxygen for growth.  With a positive RH factor test,severe anemia in the baby can develop. 

How will this influence the pregnancy and birth?

Because each pregnancy generates blood cells for each fetus’ growth, Rh-positive treatment is specific for that pregnancy. RhIg will be administered to each subsequent pregnancy as well if Rh-positive. 

It is also important to note that while Rh antibodies are antiquated with a pregnancy, there are also other instances where an RhIg shot may be needed:

  • After an ectopic pregnancy
  • After a miscarriage
  • After an abortion 
  • Abdominal trauma in pregnancy
  • A manual breech inversion
  • Any testing or surgery conducted on the baby, amniocentesis, blood sampling, or chorionic villus sampling (CVS)


 “Great,” Claudia shared with her bestie over brunch, “another reason to worry.” Finding out that she was Rh-positive shook Claudia. The idea of receiving a shot to protect her and her unborn baby, wasn’t an issue. It was the idea that her body could be attacking this beautiful being growing inside her that was the concern. 

“Nothing I say will ease that anxiety you are feeling right now,” her bestie said, breaking the silence that fell between them. “From what you’ve shared with me and what I’ve researched after you told me, this antibody is treated before your delivery and immediately after delivery. I don’t know much more, but I do know that this is something that your OB knows how to navigate.”  

(We advise to always consult with your care provider with questions and/or concerns regarding you, the pregnancy, or the baby.)