What a great question!  Ironically, there isn't a clear answer that doesn't involve opinion.  However, with that being said, I will be happy to share my own opinion on the subject!  The significance of pregnant Beloved's disappearance is that Beloved truly was a supernatural entity sent to wreak havoc on Sethe through revenge.  Beloved's true demise begins when Denver is brave enough to exit Sweet Home to find help for Sethe (in many forms).  Denver is able to outsmart the supernatural in this way, at the exact moment that Beloved is having her sweet revenge.  In my opinion, the fact that the prayer vigil is the gathering that "upsets" Beloved the most provides some proof of her as supernatural entity.  Ironically, this fact doesn't take away from Sethe being just as upset that Beloved is gone.  Luckily Paul D does end up convincing Sethe that Beloved was not, in...