I found the same thing with my last pregnancy, and yes it is worse and started much earlier this time around. I am fairly sure there has been an earlier post on this subject.
A couple of things I have found to help it go away.
1. orgasm. If you have a high risk pregnancy check this with your midwife first.
2. Getting up and going for a short walk, I usually also add a chapter from a good book and a gingernut to this prescription.
Make sure you don't have pressure on the leg most prone to the problem. I have banned my husband from resting his hand on my hip as this seems to be a trigger. He hates that as he likes the contact, but if he wants children he has to put up with it!
I also try not to think about the problem while going to sleep as I have found if I think about it my leg seems to feel it has to start up. I have also found it isn't as bad during the day, so sometimes go for a catch up snooze (when my son will let me, my MIL has looked after him a couple of times to let me do this).
Hope some of this is helpful
Rachelle, NZ, son George 10.12.02, Ian 15.06.04