Back pain is almost assured during pregnancy — studies show between 50 to 70 percent of all pregnant women will suffer pain in their lower back. As the weight of the fetus increases, your center of gravity shifts forward. To compensate for this shift in your posture, you naturally lean back, placing stress on the muscles in your lower back, which can lead to soreness and pain.
And back muscles don’t necessarily go to sleep when you do — they can stay tense if your mattress doesn’t provide proper, continuous support. Your muscles may never have a chance to relax and heal, leaving you to toss and turn at night.