The common cause of severe lumbar pain symptoms in the third trimester is lumbar disc herniation. The center of gravity shifts to the pelvis after pregnancy, and the increased load on the lumbar disc can cause rupture of the fibrous ring, and the nucleus pulposus can protrude into the spinal canal through the fibrous ring fissure to compress the spinal cord and nerve roots, causing lumbar pain. At the same time, the rupture of the lumbar fibrous retardation can stimulate the sinus spinal nerve, causing reflex pain in the lumbar region. On examination, the straight leg raise test is positive, the straight leg raise strengthening test is positive, deep pressure pain is seen in the spinous process of the lumbar spine, percussion pain is positive, the lumbar spine is restricted in forward flexion, and the lumbar MRI shows dehydration degeneration of the lumbar intervertebral disc and compression of the dural sac by protrusion into the spinal canal. Bed rest as much as possible, along with continuous hot compresses on the lumbar region, can relieve the symptoms of lumbar pain.