After pregnancy, there are many physiological changes in pregnant women. The back pain in the second month of pregnancy is caused by the enlargement of the uterus during pregnancy, pulling on the cycle tissue, and the enlargement of the uterus will compress the lumbar vertebrae causing back pain. After pregnancy, the hormones in the body will change and estrogen and progesterone will increase significantly causing the relaxation of tissues and joint ligaments resulting in lumbar pain, as long as the lumbar pain is not very serious do not worry, usually appropriate rest, pay attention not to wear high heels during pregnancy and so on can relieve lumbar pain. If there is a pre-eclampsia miscarriage can also cause back pain, you can go to the hospital to see the development of the fetus through ultrasound examination, the pre-eclampsia miscarriage needs to be timely with drugs to protect the fetus, you can use progesterone.