Why we should not extend the 14-day rule for embryo experimentation

Gradually, the chorus of voices advocating for an extension is increasing. It’s an understandable trend—because we can already experiment on embryos for up to 14 days, many people may see little harm in extending this to 28 days or more. What difference could an extra 14 days make? The embryo lives a little longer, that’s all. There are, however, numerous reasons why an extension is not a good idea.