Prenatal Antibody Testing - Rh Factor
Yes… it is another test
What is it?
The Rhesus (Rh) factor is a certain type of protein that is found on the outside of your red blood cells. This is determined by a simple blood test to find out your blood type. The positive or negative sign next to the blood type letter represents the presence or absence of the Rh factor (protein). You inherit the Rh factor (protein) from your biological parents. During pregnancy this is important to know because certain complications may arise when you’re Rh-negative and pregnant with a baby who’s Rh-positive.
When is it done?
Every pregnant woman gets the Rh factor test during each pregnancy. It’s usually one of the first and most important tests you’ll have. Ideally this is in the first trimester. The antibody screening test is only done if your blood type is negative. It will show whether your blood has any antibodies that could harm your baby.
What do the results mean?
A negative result means that no red blood cell antibodies were found.
A positive test result means that you have red blood cell antibodies in your blood.
*Data chart by Janelle Marie Barowski, 2022
How will the results influence the rest of my pregnancy and birth?
If the antibody screening test shows that there are Rh antibodies present, its likely you will have more frequent tests during your pregnancy to check the health of your baby. If you’re Rh-negative and your baby is Rh-positive, you might have a condition called Rh factor incompatibility, which can be dangerous to your baby. Their concern is if your blood and your baby’s blood mix, your body will start to make antibodies that can damage your baby’s red blood cells. This is known as Rh sensitization. It is unlikely to harm your first Rh-positive baby that you are pregnant with because you most likely will only come in contact with you baby’s blood during delivery, meaning the antibodies wont start being created until after birth. Once this sensitization takes place, your antibodies stay in your system and will attack future pregnancies if that baby is Rh-positive again.
Problems associated with Rh incompatibility can be prevented. Your provider will give you a shot of Rh immunoglobulin (RhIG) around 28 weeks pregnant. This drug stops your body from making antibodies for the duration of your pregnancy. You may need another dose of the RhIG shot within 72 hours after delivery as well.
If you’re Rh-negative and experience any spotting during pregnancy, it is very important to contact your provider. They may administer another RhIG shot because the chances of your blood mixing before baby is born is much higher.
Rh incompatibility may cause anemia and jaundice in your newborn baby.
We understand that the news of you or your baby having Rh antibodies present can potentially send your mind into a spiral of worrying about the duration of your pregnancy and health of your baby. The wonderful thing about modern medicine is that your provider should be taking all the steps needed to keep you and your baby safe, healthy and happy! If you have any worries or concerns, the best place to reach out to is your OB or midwife! The more conversation and education you can receive on the topic will help release any worries or fears so you can enjoy this time in your pregnancy and preparation for your little one!
