Human embryo research beyond the primitive streak

The authors suggest that it is time to reassess the 14-day rule, since recent technological advances have made it possible to culture human research embryos for longer periods. A justification for doing so is that the 14-day limit that emerged from US and UK policy in the 1970s and 1980s was decided when culturing embryos close to 14 days was not possible. Given the importance of studying the “black box” of human development past the 14 day mark of embryo development, the authors suggest an incremental approach to extending the rule by milestones of 2 to 3 days, with agreement grounded in public dialogue. This would be based on six principles: 1. scientific justification: culturing human research embryos beyond 14 days must respond to research goals that cannot be met by other means; 2. well-defined increments: small steps should be taken with frequent evaluations and reassessment; 3. independent peer review: research proposals should be evaluated by independent ethics committees; 4. public dialogue: researchers seeking incremental steps in embryo culture should engage in dialogues with the broader public; 5. informed consent: embryos used in research should originate in donors who previously consented for their use for extended embryo culture and research; and 6. separation of clinical care and research: undue incentives should be avoided. The authors conclude that for revision of the 14-day rule, researchers and policymakers must consider public opinion as well as the merits of each incremental step.