The interesting thing is that, at the heart of the Roe versus Wade decision , was this very question. The decision about abortion was not based on whether it was a human being, or when life began . It was solely based on when a baby is legally considered to be a person. From a legal standpoint, humanity is not the same as personhood. This is why slaves did not have full rights. They were not considered to be persons, although everyone knew they were human.
So it is interesting that the CEO of the largest abortion provider in United States has no idea when a baby actually has constitutional rights. She hints in her answer that perhaps it begins when the unborn child is viable. But the actual legal answer is that an unborn child has absolutely no legal rights until birth. That is why partial-birth abortion brings the unborn child most of the way outside of the womb before killing it. As long as the unborn child is at least partially inside the womb, it can be killed. But the second it comes completely outside of the womb , if you kill it, it is considered murder.