" Andrew thought that it was strange that humans would choose the day of coming forth from the womb as the significant thing to commemorate. He knew something of human biology, and it seemed to him that it would be much more important to focus on the moment of the actual creation of the organism, when the sperm cell entered the ovum and the process of cell division began. Surely that was the real point of origin of any person!
Certainly the new person was already alive - if not capable of independent functioning - during the nine months spent within the womb. "

― Isaac Asimov ,