Hiya Jojo
I'm O Rhesus Negative and have had the anti D injection 4 times - None of which hurt.
Try not too worry too much about adverse outcomes - Statistically only a small number of Rh-negative women (about 2 percent) develop antibodies to their baby's RH-positive blood during their third trimester, so this injection is given routinely at 28 weeks gestation.
Heres some additional info for you (I found quite informative) - Hope this puts your mind at rest somewhat.
What is my Rh status and why do I need to know it?
Early in your pregnancy you'll have your blood tested to determine your blood type and your Rh status that is, whether you have the Rh (Rhesus) factor, a protein that some people have on the surface of their red blood cells. If you do have the Rh factor, as most people do, your status is Rh-positive. (About 85 percent of Caucasians are RH-positive, as are 90 to 95 percent of African-Americans and 98 to 99 percent of Asian Americans.) If you don't have it, you're Rh-negative, and that means you'll need to take certain precautions during your pregnancy.
The problem is that if you are Rh-negative, there's a good chance that your blood is incompatible with your baby's blood, which is likely to be Rh-positive. (You probably won't know this for sure until the baby is born, but you have to assume it, just to be safe.) Being "Rh-incompatible" isn't likely to harm you or your baby during this pregnancy, if it's your first. But it does mean that if your baby's blood leaks into yours, as it can during birth, your immune system will start to produce antibodies against this Rh-positive blood. If this happens you will become "Rh-sensitized" and the next time you become pregnant with an Rh-positive baby, those antibodies may attack that baby's blood. Fortunately, you can avoid becoming Rh-sensitized as long as you get an injection of a drug called Rh immunoglobulin whenever there's a chance that your blood has been exposed to the baby's blood.
If you're Rh-negative and you've been pregnant before but did not get this shot, another routine prenatal blood test will tell you if you already have these antibodies that attack Rh-positive blood. (You may have them even if you miscarried the baby, had an abortion, or had an ectopic pregnancy.) If you do have the antibodies, it's too late to get the shot, and if your baby is Rh-positive, he's likely to have some problems. If you don't have the antibodies, then the shot will protect you from developing them.
What are the chances that my baby and I are Rh-incompatible?
If you're Rh-negative, the chances are good that you and your baby are Rh-incompatible. In fact, your practitioner will assume you are, just to be safe. Is there any way to tell for sure? If the baby's father takes a blood test and is found to be Rh-negative like you (which is a long shot), you'll know that your baby is also Rh-negative and there's no incompatibility and no need for treatment (the shot). Short of that, your practitioner will assume the baby's father is Rh-positive (because most people are) and that your baby is as well. (An Rh-negative mother and an Rh-positive father have a 70 percent chance of having an Rh-positive baby.) You won't know your baby's Rh status for sure until his birth unless you have an amniocentesis, a test that examines fetal cells from the amniotic fluid surrounding the baby in your uterus. In any case, there's no harm in getting the shot even if you don't turn out to be incompatible.
On the other hand, if you're Rh-positive and your partner is Rh-negative, you may have an Rh-negative child, but there's no need to worry about this because it's extremely unlikely that your baby will be exposed to your blood and develop antibodies. It almost always happens the other way around.
How might my baby's blood get mixed up with mine?
Normally during pregnancy, your baby's blood is kept separate from yours and very few blood cells cross the placenta. In fact, your blood is not likely to intermingle in any significant way until you give birth. That's why Rh incompatibility is usually not a problem for your first baby: If your blood doesn't mix until you're in labor, the baby will be born before your immune system has a chance to produce enough antibodies to cause any problems. However, you'll need a shot after the birth if your newborn is found to be Rh-positive, because if you were exposed to Rh-positive blood during delivery, the shot will prevent your body from making antibodies that could attack an Rh-positive baby's blood during a future pregnancy. (Your delivery team will take a blood sample from your newborn's heel or from his umbilical cord just after he's born to test for several things, including Rh factor, if necessary.) Without treatment, there's about a 15 percent chance that you'll produce antibodies; with treatment, the chance is close to 0 percent.
Since a small number of Rh-negative women (about 2 percent) somehow develop antibodies to their baby's RH-positive blood during their third trimester, you'll also be given a shot at 28 weeks that covers you until childbirth. You'll also need a shot if you have an amniocentesis or chorionic villus sampling (CVS), as there's a slight risk of the blood mixing during these procedures, or if you have any vaginal bleeding. In rare instances, your baby's blood could mix with yours if you suffer an injury to your abdomen during your pregnancy, so you'll need a shot if that happens, just in case. Finally, you'll need a shot if you miscarry, have an abortion, or have an ectopic pregnancy.
How does the shot prevent me from developing antibodies?
The shot (Rh immunoglobulin) actually consists of a small dose of antibodies (collected from blood donors) that serve to kill any Rh-positive blood cells in your system before they prompt your immune system to develop its own antibodies. (The donated antibodies are just like yours but the dose isn't large enough to cause any problems for your baby.) This is called passive immunization: For it to work, you need to get the shot within 72 hours after any potential exposure to your baby's blood and the protection will last for 12 weeks. If your practitioner suspects that more than an ounce of your baby's blood may have mixed with yours (say if you've had an accident), you may need a second shot. She'll give you the injection in the muscle of your arm or buttocks. You may have some soreness at the injection site or a slight fever. There are no other known side effects. The shot is safe whether your baby's blood is really Rh-positive or not.
What will happen to my baby if I develop the antibodies?
First, keep in mind that this is highly unlikely if you're receiving good prenatal care and are being treated with Rh immunoglobulin when necessary. Even without treatment, your chances of developing the antibodies and becoming Rh-sensitized are only about 50 percent even after several Rh-incompatible pregnancies. But if you did not get the shot and were to become Rh-sensitized and your baby was Rh-positive, he would likely develop what's called Rh disease or hemolytic disease. Your antibodies would cross the placenta and attack the Rh factor in your baby's Rh-positive blood as if it's a foreign substance, destroying his red blood cells and causing anemia. The disease can cause problems ranging from severe newborn jaundice to brain damage or, in extreme cases, even miscarriage or stillbirth. Once you're sensitized, you have the antibodies forever and you produce more with each pregnancy, so the risk of Rh disease is worse for each subsequent baby. While healthcare providers try to screen and treat as many women as they can reach, about 5,000 babies still develop Rh disease in the United States each year.
The good news is that doctors are finding new ways to save babies who develop Rh disease. Your practitioner can monitor your levels of antibodies and keep tabs on your baby's condition during the pregnancy to see whether he's developing the disease. She may check on the condition of your baby's red blood cells through amniocentesis or percutaneous umbilical blood sampling (PUBS), where a blood sample is drawn from a vein in the umbilical cord. If he's doing well, you may carry him to term without complications. After birth, he may be given an "exchange transfusion" to replace his diseased Rh-positive red blood cells with healthy Rh-negative cells to stabilize the level of red blood cells and minimize any further damage by antibodies circulating in the baby's bloodstream. (Over time these Rh-negative blood cells will die off and all your baby's red blood cells will be Rh-positive again, but by that time, the attacking antibodies will be gone.) If your baby is in distress, he may be delivered early or given transfusions through the umbilical cord. The survival rate for babies who receive a transfusion while in utero is as high as 80 to 100 percent, unless they have hydrops (a complication due to severe anemia), in which case, the chances of survival are about 40 to 70 percent.
