For the last 40 years, the rule, which is law in some countries and a guideline in others, has served as an important stop sign for embryonic research. It has provided a clear signal to the public that scientists wouldn’t grow babies in labs. To researchers, it gave clarity about what research they could pursue.
Now, however, a key scientific body is ready to do away with the 14-day limit. The action would come at a time when scientists are making remarkable progress in growing embryonic cells and watching them develop.
By allowing both normal and artificial embryos to continue developing after two weeks, the end of the self-imposed limit could unleash impressive but ethically charged new experiments on extending human development outside the womb.
The International Society for Stem Cell Research has prepared draft recommendations to move such research out of a category of “prohibited” scientific activities and into a class of research that can be permitted after ethics review and depending on national regulations.
People familiar with ISSCR processes say there is not unanimous support for withdrawing the 14-day rule, with objections coming from bioethicists and some scientists. But they are in the minority: most agree that it needs to be eased.