Sometimes does will lay down more often close to kidding because of the extra weight and such... Of course I wouldn't just write it off as extra weight until you check to make sure she isn't sick or anything.
Is she eating well? What's her temperature? How is her worm load, (how pale are her eyelids, has she had a fecal done recently)?
[Can't think of more things to check at the moment.. Anyone else?)
I would say to make sure she gets exercise everyday, and doesn't lay around all day. Goats that exercise are more likely to have a healthy birth.
Goat Lover in Arkansas