When a woman is RH negative and her husband is RH positive, there are specific implications for their children during pregnancy and delivery. To understand what will happen if you are Rh Negative and your husband is Rh Positive, it is important to understand exactly what those terms mean.
Everyone’s blood is divided into a type: A, B, AB, or O. Antigens, which are proteins on the surface of the blood cells, determine blood type. Rh factor is also found on the surface of the red blood cells. If you have the Rh factor, you are considered to be Rh positive, and if you don’t you are considered to be Rh negative.
Sometimes, if you are Rh negative and your husband is Rh positive, your baby can be Rh positive, inheriting this trait from your husband. If this happens, you may develop certain antibodies to your Rh-positive child. If your baby’s blood mixes with your Rh-negative blood, your body may start acting as though it is allergic to the baby. This is known as being "sensitized". If this happens, and your antibodies cross the placenta, they may attack your baby’s red blood cells, causing something known as hemolytic anemia. This can cause a variety of problems, even death for your baby.
If you have not been sensitized, at around the 28th week of your pregnancy your health care provider may give you a medication called RhIg to prevent sensitization. If your baby is born and is Rh-positive, you will probably be given another shot of RhIg to keep your body from producing antibodies against the Rh-positive cells that you may have encountered from your baby during delivery, as well as before.
If you do develop antibodies, your health care provider will check to see if your baby is in danger. If she is, your baby may be delivered, even early. In some cases your baby may be delivered early, or may be given blood transfusions while she is still in your womb.