What is Rh disease?

Rh disease can be a serious problem in pregnancy. It happens when substances called antibodies in the mother's blood cause red blood cells in her baby's blood to be destroyed. This can occur when the blood types of a mother and her baby do not match.

All blood has an Rh factor. This is what makes a blood type positive or negative. When you are Rh-negative, your baby may be Rh-negative or Rh-positive. If your baby has Rh-positive blood and it mixes with yours, your body will make antibodies. This is called Rh sensitization.

Most of the time, this is not a problem in a first pregnancy. But in future pregnancies, it could cause Rh disease.

A newborn with Rh disease has mild anemia and may have jaundice. In severe cases, anemia, jaundice, and swelling can be very dangerous or fatal. Some babies need to be delivered early. Some need special care in the NICU. A very sick baby will need a blood transfusion before or after birth.

Fortunately, Rh sensitization is usually easy to prevent.

That's why it's important to get your Rh status checked in your first trimester. It doesn't cause any warning signs. A blood test is the only way to know if you are Rh-sensitive or are at risk for it.

How can you prevent Rh disease?

If you are Rh-negative, your doctor gives you an Rh immune globulin shot (such as WinRho). It helps prevent your body from making the antibodies that attack your baby's red blood cells.

Timing is important. You need the shot at certain times during your pregnancy. And you need one anytime there is a chance that your baby's blood might mix with yours. That can happen with certain prenatal tests or when you have pregnancy bleeding, such as:

• Right after any pregnancy loss, amniocentesis, or CVS testing.
• After turning of a breech baby.
• Before and maybe after childbirth. Your doctor gives you a shot around week 28. If your newborn is Rh-positive, you will have another shot.