Background paper27th November 2025
The 14-day rule is a key feature of human embryo research governance in the UK. It stipulates that human embryos should not be grown for longer than 14 days after the process of creating the embryo began.
As an interim output of our project on the 14-day rule, this briefing does not draw conclusions, but aims to support discussion about the future of embryo research and how it is regulated, providing information about:
- what we know about how human embryos develop
- what embryo culture is and how it has contributed to research into early human development
- how human embryos are sourced and used in research, and how this is regulated
- what has been achieved through research involving human embryo culture
- the focus and aims of ongoing research
More information about the ethical considerations involved in the 14-day rule for embryo research in the UK is available in a separate briefing.