I am not in the "they waited for the baby to be born" camp. I really just think that is a coincidence. Now, they may have waited for Hannah to get out of the hospital or just knew she was out, so they could eliminate all of the adults. But, let's just give some thought to them waiting until the baby was born, if they did? Why wait? Well, if they did it before the baby was born, then Hannah would have been very pregnant with a full term baby. If they killed a pregnant lady, they in essence more than likely would also kill her baby, since there would be no telling how soon someone could get to the baby in the womb. So, once again....they did not want to kill the children, in the womb or out of the womb. Make sense? That is the ONLY reason I can think they would wait until the baby was born.