I was told it was due to a lack of calcium. Try to up your calcium and if you're allowed, 150mg magnesium tablet a day. I did this is and no more leg cramps.
when you get a cramp, ask your spouse to rub his head where the cramp has occured. You must think it sounds insane, but it really works. Also, try to eat a banana a day.
But you should know - its normal! ;)
It could be lack of Magnesium which is often the case during pregnancy.
Banana a day should help! Or some organic magnesium pills (mine came in liquid when I understood bananas wont be enough. Took for 5 days and it stopped. Didn't finish the whole course.)
my dear my own is worse and it only happen when I am in bed. I mostly ask my husband to gently massage my leg till the pain is gone. You shd also not stretch your legs when you are stretching in my bed. hope it works for you cuz the pain is unbearable.