Info on menstrual cups please

I have never liked tampons only used pads, And I've read a few posts now on women recommending menstrual cups. I'm pregnant now so won't need them for a while, but I would like to know about any info and experiences with them good or bad. I have never even heard about them till now and then I googled lol.. They look big and scary and makes me wonder if they will loosen the lady parts?