What is it?

Every person has one of four blood types (A, B, AB or O). These blood types are either positive or negative, based on your Rhesus factor (RhD).

Being RhD positive means you have a protein known as ‘D antigen’ on the surface of your red blood cells. If you’re RhD negative, you don’t have this protein.

If you’re RhD negative and your baby is RhD positive, problems can develop if your baby’s red blood cells cross to you. This can happen during delivery. It might also happen if you have bleeding at any stage. Miscarriage, termination of pregnancy, trauma or certain tests can cause blood cells to mix.

Your immune system sees the baby’s RhD positive blood as foreign. Your body responds by making antibodies that attack the baby’s blood cells. This is called ‘sensitisation’.

Once you are sensitised, future RhD positive pregnancies can be at risk of complications.

All RhD negative women are given an injection called anti-D at around 28 and 34 weeks. Anti-D stops you from producing the antibodies that attack your baby’s RhD positive blood.

Remember, any type of bleeding in RhD negative women is serious and needs to be treated urgently.


What will my GP do now?

Your GP will aim to work out the cause of your bleeding and make a plan to treat it. If you need anti-D, your GP will help you understand the next steps.

If your body hasn’t made antibodies, you will need anti-D:

  • If you’re less than 20 weeks, your GP will refer you to the hospital for treatment if bleeding stops before 12 weeks, you might not need anti-D
  • If you’re more than 20 weeks, anti-D can be given by the antenatal service in the hospital, delivery suite or antenatal clinic

Anti-D must be given as soon as possible after the bleeding and no later than 72 hours after. If your body has already made antibodies, this means you are RhD-sensitised. Your GP will refer you to your antenatal clinic for close monitoring and to check your baby’s condition.

In future, your GP will stay informed about your health and your baby’s health.


What can I do?

It’s very important to see your GP or lead carer as soon as you notice any bleeding. Remember that anti-D must be given as soon as possible and within the first three days after bleeding.

Bleeding can be scary, but it doesn’t mean there’s a problem. Talk to your GP to learn more about your blood type and the risks. Make sure you know who to call if you are worried or have a question, or if you notice bleeding again.