Published May 2022
Contents
― Introduction
― Key messages
― What your blood test has shown
― What is alpha thalassaemia?
― What you need to know if you are an alpha thalassaemia carrier
― What to do next if your screening test report recommends testing your baby’s father
― If your pregnancy is found to be at high risk of a serious haemoglobin disorder
This leaflet is for women who have had a test for sickle cell and thalassaemia in pregnancy and have been told they may be an alpha thalassaemia carrier (also known as possible alpha thalassaemia carrier).
As your screening test cannot confirm if you are a carrier of alpha thalassaemia, we have written the information in this leaflet as if you are an alpha thalassaemia carrier and to help you understand if further action is needed during your pregnancy.
It can be passed to your children and this is why it is important to be aware you may be a carrier.
Your test result is written as: possible alpha thalassaemia carrier
+/- iron deficiency.
Your recent blood test has shown:
Smaller red blood cells are usually caused by a lack of iron in your blood (iron deficiency) which is the most common cause of anaemia. The blood test that your midwife can offer during your pregnancy checks your ferritin levels and this helps decide if you are iron-deficient.
For someone who is healthy and has enough iron, one of the most likely explanations for the blood test result is that the person is an alpha thalassaemia carrier.
Alpha thalassaemia is one of many possible variations in your blood, called haemoglobin gene variants, that can be passed on from parent to child. Most people inherit two alpha globin genes from their mother and two alpha globin genes from their biological father.
Your genes also control the type of haemoglobin you inherit.
An alpha thalassaemia carrier has changes in one or more of these genes.
Alpha thalassaemia of different types occurs in all ethnic groups. The rates vary across the world, with some populations having higher rates of alpha thalassaemia than others.
We are unsure if you are a carrier of alpha thalassaemia. For instance, if you were already taking iron when you were tested, the ferritin test would not show low iron and your red blood cells may simply be recovering from iron deficiency.
We have written the following information as if you are an alpha thalassaemia carrier.
In pregnancy, for most women who may be an alpha thalassaemia carrier it is very unlikely that they will have a child with a serious haemoglobin disorder.
Further action is only necessary if your screening test report recommends that the biological father of the baby is tested.
This would be recommended if:
We would like to test the biological father of your baby within three working days, or as soon as possible. This is to make clear whether he is an alpha thalassaemia carrier or a carrier of any unusual haemoglobin variant.
If the biological father of your baby is not a thalassaemia carrier and does not carry any other unusual haemoglobin variant, your unborn baby, any other babies that you already have together, and any other babies that you have together in the future, should have a low chance of having alpha thalassaemia or any other haemoglobin disorder. In this case, no further action will be needed.
If the biological father of your baby is an alpha thalassaemia carrier or carries any other unusual haemoglobin variant, this could possibly be passed on to the baby from both parents. This may have serious implications for both mother and baby.
If you and the biological father of your baby are both alpha thalassaemia carriers, and if the type of alpha thalassaemia means your pregnancy is at high risk of alpha thalassaemia major, you will be invited to discuss this with a specialist midwife as early as possible in your pregnancy.
The midwife may then refer you to either a genetic counsellor or another health professional with specialist knowledge who will be able to tell you how this may affect your unborn baby.
Some alpha thalassaemia disorders are much more severe than others, and the genetic counsellor or health professional will discuss this with you
Some parents choose to have an invasive test (chorionic villus sampling (CVS) between 11 and 14 weeks of pregnancy, or amniocentesis after 15 weeks of pregnancy) to find out if the baby will have a serious haemoglobin disorder. You will only be offered this if the exact gene change has been identified in both parents.
The specialist midwife or genetic counsellor will discuss the invasive test with you.
You can get more information about thalassaemia from the following.