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The Fibromyalgic Pregnancy and Beyond - Atypical antibodies and prevention of haemolytic disease in the newborn

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Published on Saturday, 27 August 2011 14:52

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Atypical antibodies and prevention of haemolytic disease in the newborn

 Are you sitting comfortably dear reader?  There is no way to make this topic interesting so you may as well settle yourself down somewhere with lots of cushions, just in case you fall asleep while reading about this boring but vitally important information.  You will be offered a series of routine blood tests at one of your first antenatal visits.  One of these will be to determine your blood type and Rh factor. The most common blood type is Type O; the most common Rh factor is positive. People with Type O, B, A, or AB positive blood have a positive Rh factor. Those with Type O, B, A, or AB negative blood have a negative Rh factor.  Still awake?  Okay then read on…

 When your blood type is Rh negative, and your baby’s father’s is Rh positive, your baby could inherit the father’s positive blood type, which could cause a problem during pregnancy. If your blood type is Rh negative, your body’s immune system can recognize the baby’s Rh positive blood cells that escape into your circulation. As you now know, these cells are different from yours. Because they are different from yours, your body will produce antibodies to destroy your baby’s red blood cells. These antibodies not only attack your baby's blood cells that are in your circulation, but cross the placenta in an attempt to destroy your baby's blood cells in his or her circulation.

 These newly formed antibodies may not be a problem during your first pregnancy; however they can lead to a serious disease in any subsequent pregnancies.  This is known as haemolytic disease of the newborn (HDN). If your body produces a high level of antibodies, more of your baby’s blood cells will be destroyed. Eventually, this produces anaemia in your baby.  This can cause the death of your baby before birth. Live births can be complicated by severe jaundice, mental retardation, hearing loss or cerebral palsy.  Scared now?  Try not to be, the blood test I mentioned at the beginning of this section check for antibodies and if any are found, they are monitored closely throughout your pregnancy.

 The good news is that haemolytic disease of the newborn can be prevented in most cases by giving you an injection of Anti D which prevents your immune system from reacting to your baby’s red blood cells. The Anti D finds your baby’s red cells in your circulation and throws a chemical cloak over them, neutralising them so you don’t produce antibodies against your baby’s red blood cells.

 Once your blood type is determined to be Rh negative, the option of anti D should be discussed with you.  Your consent is needed to give you this injection and you need to be aware that it is a blood product, albeit a very small amount of technically ‘safe’ blood. However, some religious beliefs discourage the administration of blood products no matter how small. This injection is routinely offered to women with Rh negative blood during pregnancy and within 72 hours following birth. If your Rh factor matches the baby’s father or you are Rh positive, you have nothing to worry about because Rh disease cannot affect you or your baby under these circumstances.