The cramp remedy I used back in the football days was as follows:
Drink 10 glasses of water 3 days before the game, and everyday until 2 hrs before kickoff. The day of the game eat 3 banana’s and be sure to have an average amount of salt in that days diet. During game time drink water in small portions.
Now all these things were magic in preventing cramps. The cramps during games (any athletic activity) are caused by dehydration. How the potassium fits in I don’t know. The salt was important to make sure your body retained a adaquate amount of water in heat. The water days ahead of time made your body retain larger amounts of water, you couldn’t drink large amounts of water the day of the game, and during the game or you’d get stomach cramps.
Now if cramps from dehydration and physical activity are anything similar to those morning ones I don’t know. I have heard that it is very important to drink water in the morning (and from waking up with very dry mouths) to rehydrate you after a parched night. This implies that morning cramps are indeed caused by dehydration. I imagine potassium my act in the bodies mechanism for storing water.
Being pregnant you will need a much higher volume of water than you typically drink for obvious reasons. The sweating and constant peeing doesn’t help any either.
I would make a conscious decision to drink much more water during the day and early evening. Avoid soft drinks, caffine, and alcohol because they dehydrate you. Fruit juice, and water should help, and the oft mentioned banana. I hope this makes some sense.