Since the Human Fertilisation and Embryology Act came into force over 25 years ago it has been illegal in the UK to research on human embryos in the test tube beyond 14 days.
Recent scientific developments have raised the prospect of changing the limit. The BBC West of England Health correspondent Matthew Hill looked back at the 14-day rule which was brought in after the birth of Louise Brown.
Louise was asked to contribute to the two-part documentary, which also included interviews with Dame Mary Warnock, who set the limit and those working in present day embryo research. You can listen to the documentary here: