1. Leave that heavy stuff to the husband. If you are a single mother, get a guy to do the heavy lifting. This is your time to chill. You want to ensure that you do not strain your back due to lifting of heavy stuff. You should also watch it so that you don't bend over too much. Lifting of heavy objects and bending over too much are activities that can result in pregnancy back pain.
2. Live and let live. Actually there is a James Bond movie that has a very close title; that one is "live and let die" by Roger Moore. Anyways, my usage of the term "live and let live" in this context refers to relaxation. Try and ensure that you relax as much as possible throughout the day. Try to rest while reclining with your feet propped on a higher elevation. This will remove the pressure from your back and your back will be grateful for it.
3. Get the husband or someone to rub your back. I am a back rubbing machine, my wife ensured that I became one. You should get a back rub especially after your bath. You might want to consider buying an electric back massager if you don't have someone to rub your back, or alternatively, you might decide to pay a visit to a massage therapist.
4. Take a warm bath as soon as you feel a back pain coming on. Try to ensure that the water you use is warm and not too hot. Remember that you have a baby inside of you and you do not want the water to be too hot for him or her (or them?). Soak inside your bath tub for a while until the back pain subsides. Be very careful when you are doing all of this so that you do not slip.