Screening for sickle cell and beta thalassaemia

Deciding to have diagnostic tests

If both parents discover they are carriers, there is a 1 in 4 chance their baby will have the condition. They can choose whether to have a diagnostic test to check if the baby is affected. A woman who knows she is a carrier may also want diagnostic tests if she is not in contact with the baby's father or he does not agree to be screened. There are two types of test, chorionic villus sampling (CVS) or amniocentesis. (See 'Experience of having diagnostic tests'). CVS takes a sample of placenta for analysis, whilst amniocentesis takes a sample of the fluid round the baby. 

No-one has to have these tests. It has to be a personal decision. Some parents decide they would rather not know, especially if they feel strongly they would never terminate a pregnancy. (See 'Reasons for deciding not to have diagnostic tests'). Others want a diagnostic test because they expect that they would terminate the pregnancy if the baby has a sickle cell disorder or beta thalassaemia major.

However, some parents want a diagnostic test in pregnancy even though they feel sure they would not terminate the pregnancy. They may prefer to know for certain rather than worrying all through pregnancy whether their child has the condition. Many people also think it is important to prepare emotionally for what they may face. 

Most people we spoke to felt it was worth taking the small risk of miscarriage (up to 1% for both CVS and amniocentesis - NHS Screening programme July 2017) in order to find out.

Whilst some people decided quickly they wanted a diagnostic test, for others it was a painful process to make up their minds.

Many different factors will affect people's decision about whether to have diagnostic tests, including their personal knowledge and experience of the conditions, their moral or religious views, their feelings about what they could cope with as parents and their anxieties about what life would be like for the child. 

Some people talked about how seeing family members or friends with one of the conditions convinced them they wanted a diagnostic test. We talked to two women who themselves had haemoglobin SC disorder and who both decided to have antenatal diagnosis in some or all pregnancies. They were most concerned about the possibility of having a baby with full sickle cell anaemia, but felt they would manage with a baby with SC disorder like themselves. (See Interview 07 and Interview 03 above).

Parents who already had a child with one of the conditions had different views about whether to have diagnostic tests in future pregnancies, depending partly on how well the child was. It can be difficult for women to consider ending a pregnancy if they already have a child with that condition so some women would prefer not to know but others would consider this option.

One mother whose own daughter with sickle cell anaemia has been quite well so far knew this might change.

Religious views were an important factor for many people in reaching their decision. For some Christians and Muslims, their religion meant they could never consider ending a pregnancy. But not all people with religious beliefs felt this way. Some Christians and Muslims, and one Buddhist mother, wanted diagnosis so they had a choice whether or not to terminate, and some Muslim mothers had investigated Islamic teaching on termination. As one mother explained, some Islamic scholars teach that termination for life-threatening conditions is permitted up to 120 days of pregnancy, at which point the soul enters the unborn baby ['ensoulment']. After that it is forbidden. 

See also sections on:

'Reasons for deciding not to have diagnostic tests',

'Message to other parents',

'Deciding what to do after diagnosis',

'Values and religious beliefs',

'Advising people about their options'

'Timing and delay'.

If you would like to see more parents talking about their experiences of diagnosis in pregnancy (including diagnosis for other conditions such as Down's Syndrome), you can visit our Antenatal screening section.

Last reviewed December 2018.
Last updated
December 2018.


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