The symptoms of low back pain may be caused by the following factors: 1. It is normal for low back pain to occur during pregnancy because the uterus increases in size and presses on the surrounding tissues. 2. The symptoms of low back pain may also be caused by lumbar muscle strain, if a woman stands frequently or does frequent bending movements or heavy physical labor after pregnancy, it will lead to damage to the soft tissues of the lumbar region and cause symptoms of low back pain. It is recommended that patients seek medical attention for further examination.