M.E.
I gave birth to twins on October 26th, and went through the same thing. My girl's head was low in my pelvis for much of the pregnancy, and I was very uncomfortable. The maternity belt I used was two pieces and supported my lower back if I pulled it tight enough. But at the end I couldn't stand this for long, and reading another response it sounds like it may not be recommended. To be honest, I limited my activity as much as possible and found the least uncomfortable position at home, and always using the motorized wheelchairs at stores. After all of the postural changes of pregnancy, I had a C-section. The weakness in my core muscles and increased demands of lifting and bending has meant that the pain continued after I gave birth. Now that my babies are nearly 8 weeks old, I have finally sought out physical therapy to deal with my back pain. I HIGHLY RECOMMEND this for all women post partum. I've had only two sessions and I'm already feeling MUCH BETTER. I know this doesn't specifically pertain to your question, but I wanted to share in case your pain doesn't go away after you give birth. Best wishes to you!