UK regulator recommends extending human embryo research limit to 28 days

The UK's fertility regulator, the Human Fertilisation and Embryology Authority (HFEA) has recommended that the law should be changed to extend the 14-day limit on human embryo research.

If such a change were introduced, it would potentially enable researchers to improve their understanding of genetic conditions, miscarriage and early human development more generally. Peter Thompson, chief executive of the HFEA, announced the recommendation at the 2024 Annual Conference of PET (the Progress Educational Trust, the charity that publishes BioNews). The conference was entitled '40 Years after the Warnock Report: What Is the Embryo's Special Status?' (see BioNews 1268a and 1268b).

'Research after 14 days would lead to different insights – an understanding of early embryo development in the "black box" period, which could, for example, identify early pregnancy problems or improve our understanding of how congenital diseases start to develop,' said Thompson. 'The hope of course is that such discoveries would in turn lead to new treatment options.'

The 14-day limit has remained in place in the UK since it was enshrined in the Human Fertilisation and Embryology Act 1990. In recognition of the 'special status' of the human embryo described in the earlier Warnock Report, the Act sets out restrictions on the use of human embryos in research and treatment, setting out the circumstances in which embryos can lawfully be created and cultured. The maximum duration of human embryo culture was set at 14 days after fertilisation, or the first appearance of a feature known as the primitive streak (whichever occurs first).

The HFEA considered the case for extending the 14-day limit at a meeting in November this year, concluding that there is evidence of support for such an extension among the UK public, provided that embryo research is 'robustly regulated' (see BioNews 885 and 1213). They recommended that researchers should have the option of making case-by-case applications to the HFEA to culture embryos beyond 14 days of development, up to a maximum limit of 28 days. Such a change to the limit would require a change in the law and is therefore ultimately a matter for Parliament. In response to audience questions at the PET conference, Peter Thompson confirmed that any amendment to the law to extend the 14-day limit would also need to remove, or change, the current reference to the primitive streak.

The announcement was welcomed by Sarah Norcross, director of PET. 'The regulator has recognised that there are strong scientific and ethical arguments for culturing human embryos beyond the time currently permitted under UK law,' Norcross told the Guardian. 'Such an extension will not only help scientists to understand human biology and disease, but also maximise the usefulness of a very precious resource – embryos donated to research by fertility patients, following the completion of their treatment.'