RH Factor and Pregnancy
Some excerpts from the WebMD article:
The A, B, and O blood group characteristics are indicated by specific types of proteins found on the surface of the RBCs, as well as inside the cell and in other body fluids like semen and saliva. Blood types A and B indicate two different proteins which exist on and in the RBC. Blood type O indicates the absence of either A or B proteins. It is also possible to have both A and B proteins present in a single individual. Thus, individuals can have type A blood, type B blood, type AB blood, or type O blood. ABO blood type is the most important RBC characteristic when discussing blood transfusions, but the Rh factor is the most important when discussing pregnancy and Rh disease.
The Rh factor is a group of proteins that occur only on the surface of the red blood cell. Simply put, if you have the Rh factor present in your RBCs, you are termed "Rh positive." If the Rh factor is absent then you are termed "Rh negative." So there are generally two parts to blood typing: the ABO part and the Rh part, and people are typed as A-positive, A-negative, B-positive, B-negative, AB-positive, AB-negative, O-positive, or O-negative.
Rh disease occurs when an Rh-negative mother and her husband conceive an Rh positive child. When a few of the baby's Rh positive red blood cells cross into the mother's system via the placenta, either through a fall or accident, an amniocentesis, during a miscarriage, elective abortion, or ectopic (tubular) pregnancy, or after delivery when the placenta is removed, the mother's immune system identifies these Rh positive fetal RBCs as foreign and sets out to immediately destroy them, as well as form long-term antibodies to fight them off at a later time.
If you are an Rh negative woman and you are carrying an Rh positive child during your first pregnancy, the chance of becoming sensitized and causing a problem for the baby is small. If the baby's RBCs pass into the mother's system, her body responds by producing antibodies and she becomes "Rh sensitized." As a result, she will always carry these antibodies in her immune system.
If you carry an Rh-positive child in a subsequent pregnancy, the antibodies created by the immune system during the first exposure respond more quickly to the foreign red blood cells from the baby. These antibodies attack and destroy the baby's RBCs in the mother's circulation, but more importantly, they also cross the placenta and begin destroying the baby's red blood cells circulating in the baby's body. Remember, we all need functioning red blood cells to carry oxygen and carbon dioxide, even a baby in its mother's uterus. There are no complications for the mother in these circumstances, but there may be minor to serious complications for the baby. This is called hemolytic disease of the newborn.
There are very few places in health care where a problem has been so clearly identified and a method of prevention has been so effective. Rh disease is one of those rare opportunities to really make a difference for many mothers and their babies. If you are an Rh negative woman who is considering pregnancy, or you are currently pregnant for the first time, or you are pregnant for the second or third time, you may still benefit from the following method of preventing Rh disease during pregnancy.
Early in pregnancy a standard group of routine prenatal blood tests are done on nearly all pregnant women. Included in this panel of tests is a blood test to determine your blood type (A, B, or O), your Rh status (positive or negative), and your antibody status. In this simple test, the laboratory is looking for a reaction by specific antibodies that might be present in your blood, specifically, if you have an Rh antibody, and if you do, what is the antibody exactly. If the antibody screen is negative then you are considered "unsensitized." If it is positive, the lab goes on to identify the exact antibody. The risks for potential problems with this pregnancy are then addressed. Prevention is only necessary and effective if you are Rh negative with an antibody screen that is negative.
In this circumstance, sensitization can be prevented by giving the Rh negative woman an injection of Rh immunoglobulin (RhoGAM™) during and after pregnancy. Rh immunoglobulin is an antibody derived from human blood products, which is injected into one of your muscles, usually an arm or buttock. With this specific antibody, your immune system is fooled into thinking it has already made these antibodies and blocks your immune system from producing any more.
I have RH negative blood and was given the RhoGama shots during and after pregnancy. I've been told that having just the one set of shots makes it safer for me and any other pregnancy I might have.
It is important information about a common medical concern for couples to be aware of. For your own comfort level, Eileen, you might want to read the entire article and do some further reading on your own.