I got them too, but after the first one which woke me screaming in bed, i always could feel them coming and would do the straighten leg thing in avoidance. Heard if you drink more water and eat more patasium itll help.
I get severe Charlie horses during pregnancy. As hard as it sounds to do, if you feel one coming on, immediy straighten your leg and flex your foot and hold. It literally stops one from happening entirely. Sometimes it's hard to get it there but as soon as I do, my cramp is gone before it even gets underway.
Get them all the time ! Sounds crazy but get up & walk & it gorder away .... They suck !
Take a warm bath. But not for very long just in case you have more contractions.