There is a recommended cut off point of after 14 days after fertilization. Before day 14, the embryo the embryo has no central nervous system and therefore no senses. If we can take organs from patients who have been declared brain dead and use them for transplants, then we can also use hundred-cell embryos that have no nervous system (EuroStemCell) .
The embryo has increasing status as it develops (EuroStemCell). Whatever moral status the human embryo has for us, the life that it lives has a value to the embryo itself (EuroStemCell). If we are not sure whether a fertilized egg should be considered a human being, then we should not destroy it. A hunter does not shoot if he is not sure whether his target is a deer or a man (EuroStemCell). With that said, doctors must take into consideration with what the recommended restrictions are for when an embryonic stem cell should and should not be