Thanks for your reply. If I understand correctly, then, before 40 days one can talk about life of the embryo/fetus from a biologic but not a halachic perspective? This raises a second question — have the rabbis discussed the status of Adam after he was fashioned but before God breathed life into him?
Would it make sense to speak of death in halachic terms for an embryo (or developing fetus) before there is a circulatory system functioning? If so, what would be the principle for consideration?