Rhesus factor disease - Preventing rhesus disease

Rhesus disease can largely be prevented by having an injection of a medication called anti-D immunoglobulin.

This can help avoid a process known as sensitisation, which is when a woman with RhD negative blood is exposed to RhD positive blood and develops an immune response to it. Blood is known as RhD positive when it has a molecule called the RhD antigen on the surface of the red blood cells.

Read more about the causes of rhesus disease.

Anti-D immunoglobulin

The anti-D immunoglobulin neutralises any RhD positive antigens that may have entered the mother’s blood during pregnancy. If the antigens have been neutralised, the mother’s blood will not start to produce antibodies.

You will be offered anti-D immunoglobulin if it's thought there is a risk that RhD antigens from your baby have entered your blood. For example, if you experience any bleeding, if you have an invasive procedure (such as amniocentesis) or if you experience any abdominal injury.

Anti-D immunoglobulin is also administered routinely during the third trimester of your pregnancy if your blood type is RhD negative. This is because it is likely small amounts of blood from your baby will pass into your blood during this time.

This routine administration of anti-D immunoglobulin is called routine antenatal anti-D prophylaxis, or RAADP (prophylaxis means a step taken to prevent something from happening).

Routine antenatal anti-D prophylaxis

There are currently two ways that you can receive routine antenatal anti-D prophylaxis (RAADP):

• a one-dose treatment: where you receive an injection of immunoglobulin at some point during weeks 28 to 30 of your pregnancy
• a two-dose treatment: where you receive two injections; one during the 28th week and the other during the 34th week of your pregnancy

There does not seem to be any difference in the effectiveness between the one-dose or two-dose treatments. Your local clinical commissioning group (CCG) may prefer to use a one-dose treatment because it can be more efficient in terms of resources and time.

When will routine antenatal anti-D prophylaxis be given?

Routine antenatal anti-D prophylaxis is recommended for all pregnant RhD negative women who have not been sensitised to the RhD antigen, even if you previously had an injection of anti-D immunoglobulin.

As routine antenatal anti-D prophylaxis does not offer lifelong protection against rhesus disease, it will be offered every time you become pregnant if you meet these criteria.

Routine antenatal anti-D prophylaxis will not work if you’ve already been sensitised. In these cases, you will be closely monitored so treatment can begin as soon as possible if problems develop.

Anti-D immunoglobulin after birth

After giving birth, a sample of your baby's blood will be taken from the umbilical cord. If you are RhD negative and your baby is RhD positive, and you have not already been sensitised, you will be offered an injection of anti-D immunoglobulin within 72 hours of giving birth.

The injection will destroy any RhD-positive blood cells that may have crossed over into your bloodstream during the delivery. This means your blood will not have a chance to produce antibodies and will significantly decrease the risk of your next baby having rhesus disease.

Complications from anti-D immunoglobulin

Some women are known to develop a slight short-term allergic reaction to anti-D immunoglobulin, which can include a rash or flu-like symptoms.

Although the anti-D immunoglobulin taken from the donor blood will be carefully screened, there is a small risk that an infection could be transferred through the blood. However, the evidence in support of routine antenatal anti-D prophylaxis shows that the benefits of preventing sensitisation far outweigh these small risks.