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Haemoglobin variants

Sickle cell and Thalassaemia screening

In the first few weeks of your pregnancy, we will offer you a blood test to see if you are a carrier of abnormal haemoglobin such as sickle cell and thalassaemia.

What are sickle cell and thalassaemia disorders?

Sickle cell disease and thalassaemia major are serious, inherited blood disorders. They affect haemoglobin, a part of the blood that carries oxygen around the body. People who have these conditions will need specialist care throughout their lives.

Sickle cell disease

People with sickle cell disease:

can have attacks of very severe pain

can get serious, life-threatening infections

are usually anaemic (which means that their bodies have difficulty carrying oxygen)

need medicines and injections when they are children and throughout the rest of their lives to prevent infections.

Thalassaemia major

People with Thalassaemia major:

are very anaemic (their bodies have difficulty carrying oxygen)

need blood transfusions every four to six weeks

need injections and medicines throughout their lives.

There are also other, less common, haemoglobin disorders. Many of these are not as serious.

How are haemoglobin disorders passed on?

Sickle cell and Thalassaemia are inherited disorders that are passed on from parents to children through unusual haemoglobin genes.  People only have these disorders if they inherit two unusual haemoglobin genes– one from their mother, and one from their father. People who inherit just one unusual gene are known as ‘carriers’ (this is known as a ‘trait’).

Carriers are healthy and do not have the disorders.  But if a carrier has a baby with someone else who is also a carrier (or who has one of the disorders), there is a chance that their baby could inherit a disorder.

Who can be a carrier?

Anyone can be a healthy carrier; but, you are more likely to carry the unusual genes if your ancestors came from places where malaria has been common. This is because being a carrier can help to protect people against malaria.  This means you are more likely to be a carrier if your ancestors came from the Mediterranean (for example Cyprus, Italy, Portugal, Spain), Africa, the Caribbean, the Middle East, India, Pakistan, South America or South and South-East Asia.

What tests are involved?

Screening involves having a simple blood test. Ideally the best time to have the test is before you are 10 weeks pregnant.  You will be offered a blood test for Sickle Cell and Thalassaemia at your booking appointment with your midwife. Your midwife will complete a questionnaire to find out where your family – and the family of your baby’s father – come from. This will help the Laboratory to determine if we need to offer screening to your partner to establish if there is a risk that your baby could be affected with a serious haemoglobin disorder.

Screening test results:

Screen negative results will be given to you at your first appointment with your midwife after your booking appointment.  This is usually around -16 weeks of pregnancy.

If you are found to be a carrier of Sickle Cell or Thalassaemia (or other rare haemoglobin disorders) you will be contacted by the Screening midwife and offered an appointment where they can explain the results to you, and offer screening to your partner.

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