I don't want to speak for fannishliss, but the episode seemed to suggest that the girl's body was being used as a vessel, not to literally birth the Mother (but maybe you're suggesting a more metaphorical rebirth?), and thus might burn out, like Nick's body when it was inhabited by Lucifer last season.

But it is ironic: a virgin is required to host the Mother. Or maybe she wants to make a new line of beings, and thus needs a virgin body. Hm...!