Sex selection

What is sex selection?

The term ‘sex selection’ is used to refer to various processes that allow you to choose the sex of an embryo.

In the UK sex selection is only allowed for medical reasons,  for example, to avoid giving birth to children with a sex-linked genetic disorder like Duchenne muscular dystrophy. These diseases affect boys but not girls (girls may still ‘carry’ the gene for the disease but they will not suffer from it). 


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Is sex selection for me?

The only situation in which you should be advised to use sex selection is in the case of medical need, such as being at risk of passing on a known genetic disease that affects children of one sex only.  In this case, it is acceptable to select the sex of an embryo so it will be unaffected by the disease.

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How does sex selection work?

In the UK, Pre-implantation genetic diagnosis (PGD) is currently the only method used in practice to choose the sex of the baby.

You may hear about the other methods listed:

Sperm sorting – this is where sperm are selected according to whether they carry male or female chromosomes.

A sample of the chosen sperm is then used to inseminate a woman or create IVF embryos in the lab. The only method of sperm sorting that is currently permitted in the UK is flow cytometry, which uses fluorescent dye to separate sperm carrying male chromosomes from those carrying female ones.

This method is not 100% reliable, so it is not used in practice.

Folklore and ‘natural’ methods such as the timing of intercourse to favour the conception of a child of a particular sex.

Selective abortion of foetuses that are shown by ultrasound to be the sex that is not wanted.

Since the changes to the EU law in July 2007, all clinics that offer sperm processing must be licensed by the HFEA and must only offer sex selection for medical reasons.

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What are the risks of sex selection?

Most of the risks involved in sex selection treatment are similar to those for conventional in vitro fertilisation (IVF). For more information, see:

With sex selection, there is also the possibility that:

  • some embryos may be damaged by the process of testing
  • no embryos are suitable for transfer to the womb after sex selection (i.e. all embryos are of the sex being selected against)
  • flow cytometry is not 100% reliable, which is why it is not normally offered.

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New genetic testing techniques

Some scientists are developing genetic tests that look for the specific genes that cause sex-linked disorders, such as Duchenne muscular dystrophy or Haemophilia A. 


This means that you may be able to select male or female embryos that do not carry the gene for the disease, instead of just selecting against all male embryos. 


For more information contact your clinic.

Page last updated: 01 April 2014

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