This is amazing and really cool but I'm wondering why they even decided to use an older embryo in the first place? Like, did they run out of new ones? I'm assum

This is amazing and really cool but I'm wondering why they even decided to use an older embryo in the first place? Like, did they run out of new ones? I'm assuming the doctors told the mother that it was the only choice and she consented knowing it may not work?