Since retrieving eggs from the mother is a complex process and not without dangers, the fertilised eggs which are not inserted in the womb are kept in case the initial implantation fails and the couple decides to try for a child again or if they decide to have more children following a successful implantation. The eggs which are frozen and may not be used for implantation are at the centre of the debate. They comprise a specific group, as they were created for medical reasons before June 2002.