Cramp and Twitchy legs especially at night. During pregnancy leg cramps are often caused by calcium or magnesium deficiency (too little), sometimes combined with low salt (sodium levels) and poor circulation which can make things very uncomfortable and annoying.
Pregnant women often can wake during the night with sudden and severe leg or foot cramps.
Or some pregnant women find that when they get into bed they experience the most annoying twitching feeling. I have had it described like "ants crawling around inside your legs"
Milder cramping can be experienced while exercising or on changing position after being still for a while.