As your pregnancy progresses, your sense of gravity also changes, sometimes quite radically. This change can put a lot of stress of your lower back. Your lower back muscles are placed under a great deal of strain, and this causes discomfort and pain. The best treatment for backache is prevention from the start.
Your doctor should be able to give you a list of exercises for you to do. This should strengthen your lower back. There are also several things for you to follow that may also help:
If your backache persists, it is important to consult with your doctor to make sure that there is no damage to your disc or spine. If you are careful in caring for your back early in pregnancy, you should have a much easier time as your pregnancy grows.