What does it mean to be Rh-negative?

Being Rh-negative means you don't have a certain protein ("D antigen," or the Rh factor) on the surface of your red blood cells. If you do have it, you're Rh-positive. So the terms Rh-negative and Rh-positive are just ways of further pinpointing what type of blood a person has, beyond the general blood type categories of A, B, AB, and O.

If you're Rh-negative and carrying a baby who is Rh-positive (like the baby’s father), your immune system, which fights off invaders to keep you healthy, will recognize your baby's Rh-positive red blood cells as foreign to your Rh-negative blood and will begin producing antibodies intended to destroy your baby's blood cells. If this is your first pregnancy, chances are everything will be fine. These crusading antibodies usually are not dangerous until subsequent pregnancies, when they've had time to grow in strength and number. This is why you have to worry about the future now. Once the antibodies begin attacking, they can lower a baby's red blood cell count, which can lead to jaundice, anemia, mental retardation, and heart failure. In the most severe cases, it can be fatal in utero (during pregnancy) or shortly after delivery. This condition is known as Hemolytic Disease of the Newborn (HDN), and for Rh-negative women, all future pregnancies are at risk. Fortunately, treatment can virtually eliminate the risk.

CAN MY ANTIBODIES HURT MY BABY?
Yes. The antibodies formed to protect you against Rh-positive red blood cells can pass to the baby you are carrying. They attack and destroy the baby’s Rh-positive red blood cells, causing anemia (low red blood cell count), jaundice, and in severe cases, heart failure. This condition is known as hemolytic disease of the newborn, or HDN.

WHO IS RH-NEGATIVE?
Most people are Rh-positive -- 85 to 99 percent. Percentages vary between ethnic/racial groups. For the 1 to 15 percent who are Rh-negative, their blood type causes no special health concerns and becomes important only when they give or receive blood and, most importantly, during pregnancy. When an Rh-negative woman and an Rh-positive man conceive a child, Rh status becomes especially important.

Source: Reid ME, Lomas-Francis C. The Blood Group Antigen Facts Book. New York, NY: Academic Press, 1997.

HOW CAN I PROTECT MY BABY?
Helping parents care for their babies with innovative products has been a Johnson & Johnson concern for more than a century. You can protect your baby (and any future babies) by receiving RhoGAM^® Ultra-Filtered PLUS Rh_o(D) Rh-immune globulin shots, which prevent Hemolytic Disease of the Newborn by keeping your immune system from making antibodies against Rh-positive cells. Once these antibodies develop, treatment with an Rh immune globulin cannot eliminate them. However, the production of Rh antibodies can be PREVENTED by receiving RhoGAM^® Ultra-Filtered PLUS during pregnancy. Your health-care provider will give you a shot at around 28 weeks of pregnancy and again after delivery if your newborn turns out to be Rh-positive (if the baby is Rh-negative, there's no need). You may also receive RhoGAM^® at other times during pregnancy when it's likely you'll come into contact with your unborn baby's blood, such as during amniocentesis and/or after any injury to the abdomen.

In addition, it's crucial that Rh-negative women receive RhoGAM^® or MICRhoGAM^® following a miscarriage or terminated pregnancy. The Rh factor is present on fetal red blood cells at just eight weeks' gestation. So even if a pregnancy ended in the first trimester, the immune system still will have had time to begin making antibodies to Rh-positive cells. Without treatment with RhoGAM^® following any terminated pregnancy, even a first full-term pregnancy can be dangerously affected.

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