The Rh Factor
In The Beginning...
When you are pregnant and have your prenatal tests, one of the first screenings done is to determine your blood type and the Rhesus (Rh) factor in your blood. Human blood is divided into four major groups, A, B, AB, or O. The type of antigen or protein that is on the blood that causes a response from the immune system determines these groupings. The Rh factor is a type of protein which is common on the blood of most people. Those with the Rh factor are considered to be Rh-positive. It makes sense that those without this protein are determined to be Rh-negative.
And Your Point Is?
What does all of this have to do with being pregnant? It means that certain precautions need to be taken to ensure your baby arrives safely. The fact is that if you are Rh-negative, it is likely your blood will be incompatible with your baby's blood. Of course, barring an amniocentesis to determine the baby's blood type, you won't know it until the baby is born. If the baby's father is Rh-positive, and you are Rh-negative, you can safely assume the baby will be Rh-positive. If both you and the baby's father are Rh-negative, then you have no concerns because the baby will likely be Rh-negative as well.
This Is Your Baby, Not Your Enemy
To be Rh-incompatible does not carry a great deal of concern during the first pregnancy. However, if the baby's blood happens to leak into your blood, which can happen at certain times during the pregnancy and birth, your immune system will see the baby's blood as a foreign invader and will produce antibodies against the Rh-positive blood. This process renders you Rh sensitive, which means that the next time you are pregnant your body will be prepared to defend you against the foreign invader and will do so by attacking your baby's blood. The good news is that you can avoid this situation by getting an injection of Rh immune globulin, which will neutralize the antibodies and eliminate the danger to your baby.
There Is Protection For Both Of You
The Rh immune globulin shot is a small dose of antibodies that kill Rh-positive blood cells in your system and then cue your immune system to produce its own antibodies. Although the antibodies are donated, they are just like yours, but the dosage is small enough that it won't bother the baby. This is what is known as passive immunization. In order for it to be effective, you have to have the shot within 72 hours of any potential exposure to your baby's Rh-positive blood. This protection is good for three months. If there's a chance that more than one ounce of your baby's blood mixed with yours, then you will need a second injection. The shot is safe regardless of the baby's Rh factor.
While there is an extreme chance your baby's blood will cross over into your blood and you develop antibodies against his/her blood, if you have good prenatal care and are being treated with Rh immune globulin when necessary, then both you and any future pregnancies you may have should progress well and without problems.