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Critical for Pregnancies: Knowing your blood type and Rh factor

During surgeries and transfusions, you need to receive compatible blood; that’s why it's important to find out what your blood type and Rh factor are in case of an emergency.

And if you’re embarking on the journey into parenthood, it’s especially important for your unborn child’s health to know your Rh factor during pregnancy.

When you donate blood, you will find out your blood type, which includes something called an Rh factor—the positive (+) or negative (-) after your A, B, O or AB blood type. People who are Rh-positive have a certain protein on their blood called the Rh factor, and Rh-negative folks do not have this protein.

Along with blood type, Rh factor plays an important role if you receive a blood transfusion. Both blood type and Rh factor must be compatible in the blood you receive so you don’t have a reaction to the transfusion.

How Rh factor affects your pregnancy

If your blood is Rh-negative and there is a possibility your unborn baby will have Rh-positive blood, any mingling of your blood with your child’s blood can cause problems.

Your body will interpret the Rh protein as a foreign substance and may create antibodies to fight the “intruder.” While these antibodies can cause serious harm to your unborn child, your doctor can advise you on what needs to be done throughout your pregnancy to greatly reduce or eliminate the risk.

Usually, there isn’t time for enough antibodies to develop during your first pregnancy, but the Rh factor difference should still be addressed as early as possible so it doesn’t affect any future pregnancies.

How to find out your Rh factor

You have a couple of options for finding out your Rh factor.

If you are not pregnant, you can find out your Rh factor by donating blood at Vitalant (pregnant women or those who have been pregnant in the last six weeks cannot donate blood). If you have previously donated blood, you have been typed and your Rh factor will be indicated by the (+) or (-) after your blood type. Alternatively, your doctor can order a blood test.

If you’re Rh-negative and your spouse is Rh-positive, there’s a good chance your baby will be Rh-positive. We’d recommend finding out your blood type–and especially if you’re Rh-negative, asking your doctor if you need an antibody screen to check if you have made the antibodies yet.

If you haven’t made antibodies, your doctor will likely order an injection of Rh immune globulin to prevent you from making antibodies during pregnancy. You will need an injection after the birth as well.

The role of blood transfusions

If your body has already made antibodies, your pregnancy will need to be monitored closely. Thanks to modern medicine, though, blood transfusions can be given to your unborn child during pregnancy through the umbilical cord, or shortly after birth if necessary.

Blood transfusions for mother or baby can be lifesavers during or after childbirth if there are other complications as well. That is why it’s important for people who are eligible to donate blood to do so regularly—to ensure blood is always available for all patients.

If you or someone you know wants to find out more about donating blood, please visit our website for answers to your questions.

Good luck as you embark on your beautiful and wondrous journey into parenthood!

Check out the other articles in our blog for tips on preparing for your blood donation, stories about patients who needed blood transfusions, fun factoids, and more.

By Dr. Ralph Vassallo, Vitalant Chief Medical Officer