HEW Support of Research Involving Human In Vitro Fertilization and Embryo Transfer: Report and Conclusions

This U.S. government report is widely acknowledged to contain (on pages 106-107) the first imposition of a two-week limit on culturing human embryos. It reads "The Ethics Advisory Board finds that it is acceptable from an ethical standpoint to undertake research involving human in vitro fertilization and embryo transfer provided that . . . no embryos will be sustained in vitro beyond the stage normally associated with the completion of implantation (14 days after fertilization)." However, the two-week limit established—apparently independently—in the later Warnock Report became the precedent for most of the spread of the 14-day rule.