UK Scientists Seek to Further Embryonic Research with Legislative Changes

UK Scientists Seek to Further Embryonic Research with Legislative Changes

UK scientists are now seeking to extend the time frame for cultivating embryos from 14 days to 28 days, hoping that the change will open doors to new medical discoveries and understanding of embryo development.1,2,3 However, the push from the scientific community to adopt the 28-day limit has caused many to question where the line should be drawn regarding human embryo research.

The 14-day limit was first publicized by British philosopher Mary Warnock, who proposed the number in her commission's report of embryonic research in 1984.2 The limit would allow for research to go on, but within a strictly controlled time frame to protect the rights of the embryo. In 1990, Warnock’s proposal was adopted in the Human Fertilisation and Embryology Act.2,4 For over 25 years, the legislation has permitted scientists to create embryos through IVF for the purpose of research, but experimentation is limited to 14 days.

For decades, the 14-day limit was merely theoretical, as no technique came close to keeping an IVF embryo alive for that long.5 With an average survival time of 3 to 5 days for an embryo in a laboratory setting, there was little reason to extend the limit.5 However, in May of this year, a group of researchers at Cambridge University led by Magdalena Zernicka-Goetz successfully kept an embryo alive outside the womb for 13 days in a specifically oxygenated environment, according to the group’s report in Nature.1,3,5 “When we reached the 13th day, we stopped the experiment because we were so near the legal limit,” said Zernicka-Goetz.5 Compared to the previous record of 6 days, the recent achievements of the research team have led scientists to seek an extension of the 14-day limit, since the fourteen day mark is within grasp for the first time.3

According to embryonic researchers, extending the allowed research period on embryos could give major insights into the differentiation of stem cells, early human development congenital conditions, heart disease, and some cancers.2,3,4 The proposal to change to a 28 day limit was recently made at the Progress Educational Trust by the Francis Crick Institute’s fertility expert, Professor Robin Lovell-Badge, and the head of the CARE Fertility Group, Professor Simon Fishel.2 If the limit for embryo research was extended to the 28 day mark, “the benefits for medical research would be enormous,” according to Fishel.5 “Certain tumours, developmental abnormalities, miscarriage: there is a whole raft of issues in medical science that we could start to understand.”2 Fishel points out that there is only so much that can be understood through examining animal embryos, so changing to 28 instead of 14 days could allow for key understandings about various medical issues and human development in the future.5

Lovell-Badge also discussed how expanding the limit could result in far greater understanding of the stage in embryonic development called the “black box” that occurs from days 7 and 28.5 “During this time, all sorts of critically important stages in the development of a human take place,” reports Lovell-Badge, including gastrulation, in which “the three main tissue layers are formed as the biological foundations for the specialised tissues of the nervous system, muscle and blood, and lungs and intestines.”2,5

Researchers know far more about this crucial stage in other animals than they do in humans, something Lovell-Badge points out in his argument for extending the time limit on embryo research.,5 Zernicka-Goetz acknowledged this lack of understanding as well, stating, “We really do not know how human embryos develop in the period between the seventh day and fourteenth day of conception. Now we have the chance to do that- with enormous benefits for medicine.”5 Studying embryos in a later stage could allow scientists to determine key biomarkers in development, which, according to Zernicka-Goetz, means doctors may one day be able to predict which embryos will do better than others, improving IVF pregnancy success rates.5

Despite the many proposed benefits of extending the embryo research limit to 28 days, the issue still remains highly contentious, and many fear that changes to the existing legislation will lead researchers to increasingly uncertain, ethically ambiguous territory. Opposition includes Mary Warnock herself, who originally proposed the 14-day limit in the 1980s. “We should note that every time the law about embryo research has been changed or amended the opposition has rallied its forces, and I think it would do so again if we try to get the 14-day rule extended,” Warnock commented.2

Fearing that all the progress made since the 1990s will be lost amidst the opposition to the 28-day plan, Warnock wants to keep the 14-day limit, which still allows for some research to be done on embryos, although not during the full critical period.2,5 “Before 14 days, it is absolutely certain- beyond any doubt whatsoever- that there are no beginnings of a spinal cord in an embryo,” Warnock stated regarding the reasoning behind the original limit.5 Still, Warnock admits that the number was somewhat arbitrary: “It could have been a different number, but not a very different number: 12 or 16 perhaps.”3,5

Within some religious groups, day 14 of embryonic development is viewed as the official start of personhood during which God bestows an individual’s soul, as the embryo can no longer split into two identical twins at this point.3,4 The proposed 28-day limit has been heavily opposed by many religious communities, who have expressed concern over the rights of the embryo, beginning even at the moment of conception. Professor David Jones, director of the Anscombe Bioethics Centre, emphasized this concern, arguing, “The 14-day limit is not philosophically defensible. I don’t think there is a difference between a 10-day-old embryo and a 20-day embryo in terms of its moral status.”1,5

Some opponents also worry that moving from a 14 to 28 day limit will spiral into a total collapse of regulations for embryo research.2 “That is why I want the 14-day rule to remain in place,” noted Warnock. “You cannot successfully block a slippery slope except by a fixed and invariable obstacle, which is what the 14-day rule provided.”5 Despite this worry, Lovell-Badge assured that “the move to 28 days would be the last change we would need to make in controlling embryo research,” as sources besides embryos already provide sufficient information about later development.1,2 If the 28 day proposal is rejected, “The alternative is to lose a very important source of information that would bring major improvements to our understanding of congenital conditions and other ailments,” said Lovell-Badge.5



  1. Cook, Michael. “UK scientists to push for 28-day limit on cultivation of embryos.” BioEdge. Published December 10, 2016.

  2. McKie, Robin. “Row over allowing research on 28-day embryos.” The Guardian. Published December 4, 2016.

  3. Allen, Victoria. “Double the time limit for embryo trials, say experts: Increasing limit to 28 days could give scientists clues on genetic defects and miscarriages.” Daily Mail. Published December 7, 2016.

  4. Harris, John. “It’s time to extend the 14-day limit for embryo research.” The Guardian. Published May 6, 2016.

  5. McKie, Robin. “A leap forward or a step too far? The new debate over embryo research.” The Guardian. Published December 4, 2016.

The Debate Over Access: Studies Suggest Abortion Has Minimal Effects on Mental Health of Mothers

The Debate Over Access: Studies Suggest Abortion Has Minimal Effects on Mental Health of Mothers

Nuclear Sequencing Redefines Giraffe Species

Nuclear Sequencing Redefines Giraffe Species