Rhesus Factor: What You Need To Know
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Testing of the Rhesus factor is part of routine antenatal care, but many women don’t know what the Rhesus (Rh) factor refers to or why it’s important. Understand more about the relevance of Rh testing here.
What is Rhesus factor?
The Rhesus factor is an antigen, or protein, found on the surface of blood cells. There are only two possibilities, either you have the Rh factor, or you don’t. Your Rh status is genetically determined. There is no ‘better’ Rh status to have, it is simply a matter of whether or not this particular molecule is present in your body.
Why does the Rh factor matter?
Most people are aware of the fact that people have different blood types like A or B. The presence or absence of Rh factor is important in the same way that blood groups are important, because in certain pregnancies there may be Rh incompatibility.
What is Rhesus factor incompatibility?
Rhesus factor incompatibility may happen when a mother who is Rh factor negative has a fetus who is Rh factor positive. Generally the maternal blood and the fetal blood do not come into contact during pregnancy, but a small amount of contact can happen around the time of birth. When the mother’s blood comes into contact with the baby’s blood, antibodies in her blood will see the Rh factor as a foreign and potentially harmful substance that needs to be destroyed.
This defensive cellular behaviour only happens after previous exposure, so you won’t have trouble with your first pregnancy but you may encounter trouble in a subsequent pregnancy, as your body is now primed to attack the ‘invader’. Rhesus incompatibility cannot happen if the mother is Rh positive or if the baby is Rh negative.
How is Rhesus incompatibility managed?
If Rh incompatibility occurs, the consequences can be very serious. The baby will develop haemolytic anaemia, and will have too few red blood cells to meet oxygen requirements. To prevent these complications, women who are at risk of Rh factor incompatibility are given Rh immune globulin. This stops your body from launching an attack by familiarising your immune system with the Rh factor.
The information in this article is intended for general purposes only. If you have any concerns about your health or the health of your child, you should always consult with a healthcare professional.