Thanks Sonali

It's a normal pregnancy situation. As the weight increases in the front of the abdomen and the uterus grows the curvature in your back increases. This is not natural for the back and hence you could say that the spine is now maintaining a different posture than what it is supposed to. When you lie down on your back the curve now is a little more and the back is not able to.find a resting position and hence feels the pain. Added to this is the pregnancy hormones which cause the aches and pains due to circulation issues.

Thanks Tina for sharing

i am also facing the same problem. since i was facing this before pregnancy also, doctor said it will increase in pregnancy.