Rh Factor

R is for Rh Factor

The Rh Factor is an inherited protein that may be found on the surface of your red blood cells. If your blood cells contain this protein, you are said to be Rh positive (Rh+), and if your red blood cells lack the protein you are Rh negative (Rh-). Inheritance of the gene responsible for producing the Rh protein follows a Mendelian pattern of inheritance, with + being the dominant trait. If you are Rh+, you can have one or two of the Rh+ genes. If you are Rh- you have no Rh+ genes. One gene is inherited from each of your parents. The three times your Rh status becomes a concern are: when you’re donating blood, when you’re receiving blood, and when you are pregnant.

The Rh Factor and Pregnancy

If you are Rh- and your partner is Rh+ there is a 50/50 chance your baby will be Rh+. If you and your baby have different Rh types, it is known as Rh Incompatibility. Rh Incompatibility can cause problems if your blood comes in direct contact with your baby’s blood. This could happen in a number of ways, including:

  • amniocentesis or chorionic villus sampling (CVS)
  • manually turning a breech baby before delivery
  • miscarriage
  • ectopic pregnancy
  • induced abortion
  • trauma during pregnancy

Your body would make anti-Rh antibodies which can cross the placenta and attack your baby’s blood. This is usually not a serious concern during a first pregnancy as there is not a lot of time for your body to make a significant amount of antibodies. However, Rh Incompatibility could be life-threatening to subsequent pregnancies (and is known as hemolytic or Rh disease).

How are Rh problems prevented?

Preventive treatment during a first pregnancy is not uncommon. This is done to avoid the chance of your body making anti-Rh antibodies. If it has been determined (via blood test) that antibody production has begun, your provider will likely suggest you receive Rh immunoglobulin (RhIg). This will prevent your body from making any more antibodies against Rh+ blood. Typically this is given around 28 weeks gestation and within 72 hours after delivery of an Rh+ baby to an Rh- mother.

If you do not receive treatment, your baby may develop anemia due to the attack and destruction of red blood cells. Depending on how severe the anemia is predicted to be, your baby may need an in-utero blood transfusion, may need to be delivered early, or may need a blood transfusion immediately after birth.

Because we firmly believe in informed consent, here is the link to the package insert for the RhoGAM injection. As always, speak with your provider to obtain the brand information for the injection they would use so you can obtain the appropriate, accurate, information before making your decision.




The information contained in this article is for educational purposes only. It is not meant to diagnose, treat, cure, or prevent any disease or take the place of consultation with a healthcare provider.

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