Embryo Research in the U.S.

This shows that you can get a pregnancy started, or at least trigger the macaques hormonal system to think that it's pregnant. Embryo research is especially controversial in the U.S., where it has faced religious objections for decades. Several countries have legal restrictions against growing human embryos past 14 days after fertilization. In 2021, the ISSCR relaxed the 14-day rule to consider experiments on a case-by-case basis.