I stretch slowly while laying down and if it pops, it pops. But I don't do any more than that because I don't want to pull a muscle.
I actually just popped my back! Lol I was sitting in my chair and just arched my back and I very nicely popped for me. Sometimes it hurts right before it pops but oh so much better. Sometimes I sit in my garden tub and arch my back over that for a tougher pop. I've never had it cause me a problem or a reaction from baby.
Oh and you can aleays check with masuses (sp?) And chirpractors that are trained for prenantal stuff. I know of a few where I am and they actually have the bed thing with a belly cut out. :-)
I used to arch and pop my back that way on the couch all the time lol but I feel like if I do it know it'll feel very uncomfortable because of my belly even though it's not that huge. Last night I was lying down and raised up my leg to the side & it popped loudly even the baby kicked as if saying "cut it out" hahaa. I will try to find a chiropractor though.
Try going to a chiropractor and having them do it for you. My brother is chiropractor and he will give adjustments up until delivery. Also look into getting a massage. Soaking in a tub or pool will help too.