Scientists call for review of 14-day embryo research rule

The UK's 14-day legal limit on human embryo research should be the subject of public discussion, researchers have said.

Currently, scientists in the UK are only permitted to allow human embryos to develop for 14 days in the laboratory (not including any time during which the embryo is frozen). While researchers can resume studying human development two or three weeks later, via pregnancy scans and material donated from terminations, this leaves a gap in our understanding of human gestation and development. Researchers made the point to the Guardian newspaper that studying embryos beyond 14 days in the laboratory could improve understanding of the causes of miscarriage and congenital abnormalities.

'The period from two weeks to four weeks has been labelled the black box of embryo development,' said Dr Peter Rugg-Gunn from the Babraham Institute in Cambridge to the Guardian. 'There's no practical way to study this currently so our knowledge is really limited. Studying embryos beyond the 14-day limit could bring benefits to patients. The sooner it could be allowed, the sooner patients could benefit in the UK.'

The restriction is based on earlier guidelines, which were incorporated into UK law in 1990. However, the International Society for Stem Cell Research suggested in its 2021 guidelines that the restriction could be loosened, in jurisdictions where public opinion supported a change (see BioNews 1097 and 1098). A report published in October 2023 showed that the UK public was open to the possibility of doubling the limit (see BioNews 1213). More recently, the Health Council of the Netherlands has recommended that the limit be doubled in Dutch law (see BioNews 1214 and 1218).

'Human embryos … are a scarce and precious resource,' Sarah Norcross, the director of PET (the Progress Educational Trust) told the Guardian. 'Is it right that scientists are legally obliged to stop studying these embryos in the laboratory after 14 days, when we could learn so much more from them, and when we could use this knowledge to better understand pregnancy loss and disease?'

At the PET Annual Conference in December 2023, a case was made by Professor Kathy Niakan – a developmental biologist at the University of Cambridge – for the development of a national research embryo bank in the UK (see BioNews 1219 and 1220). This would facilitate both donation of embryos to research by patients, and access to these embryos by researchers.

Professor Niakan told the Guardian that embryo research was crucial for improving our understanding of pregnancy: 'There's an immunological interaction that's really unique at that time of pregnancy', she said. 'There's this really interesting question of why, in some cases, the maternal cells and the fetal cells can't coexist without some sort of attack or failure.'

Meanwhile, the Guardian has also reported on the large number of frozen eggs stored by fertility clinics in Australia, that are never used in treatment or in research. Researchers in Australia are calling for rules to be reviewed, so that patients there have the option of donating unused eggs to research.