If You Are Rh Negative

Healthcare provider giving woman injection in arm.
A Rho(D) immune globulin injection protects against Rh disease in this and future pregnancies.

If you’re Rh negative, ask your healthcare provider about getting treated with medicine. Even if you miscarry or don’t deliver the baby, you'll still need treatment. The health of any baby you have in the future depends on it.

When are you treated?

If your blood has not formed Rh antibodies, you’ll be treated during week 28 of your pregnancy. You also may be treated any time there’s a chance that your baby's blood has mixed with yours. This might be after a prenatal test called amniocentesis. Or it might be if you have vaginal bleeding before 28 weeks. Treatment is a shot of medicine (called Rho(D) immune globulin). This medicine stops Rh antibodies from forming. It won’t harm you or your baby. After you give birth, your baby’s blood will be tested. If it’s Rh positive, you’ll be given the medicine again in 3 days. If it’s Rh negative, you won’t need the medicine until your next pregnancy.

Preventing future problems

Your chance of forming Rh antibodies grows with each pregnancy. This is true even for an ectopic pregnancy (the fertilized egg is outside the uterus). It's also true for pregnancies that end in miscarriage or abortion. In these cases, you will most likely get the Rho(D) immune globulin medicine. This is because your body can make Rh antibodies even if you don’t deliver a baby. Rh antibodies can cause problems in future pregnancies.


If antibodies have already formed (sensitization), Rho(D) immune globulin can’t protect the baby. You and your baby will need special care during pregnancy. Your healthcare provider will explain the details to you.

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