Sex selection is offered only where there is a medical reason, such as a family history of a condition linked to the X or Y chromosome. In these situations preimplantation genetic testing (PGT) during an IVF cycle allows embryos to be screened before transfer.
The process involves IVF, a small biopsy of cells from each embryo, laboratory genetic testing, and transfer of an embryo that is free of the condition concerned. Counselling is provided beforehand, and any testing is carried out within the relevant ethical and legal framework.