Lumbar pain in more than 6 months of pregnancy may be a normal physiological reaction caused by the uterus pressing on the lumbosacral region, or it may be caused by myositis, lumbar disc herniation and other pathological reasons. 1. Physiological phenomenon: pregnant women in the sixth month of pregnancy, due to the uterus after the increase in size, pressure and stimulation of lumbosacral nerves, resulting in increased lumbar load, resulting in lumbar pain, if there are no other symptoms of discomfort, it is a normal physiological phenomenon. 2. Myositis: Myositis is a common aseptic inflammation of the muscle fiber tissue and fascia, mostly in the neck, shoulder, back and other parts of the body, mainly manifested as widespread pain, soreness, heaviness and numbness, etc., pregnant women’s back pain may be caused by myositis. 3. Lumbar disc herniation: lumbar disc herniation is a common and frequent disease in spinal surgery, which is one of the most common causes of lower back pain and lumbar and leg pain, and most of the patients manifested lumbago and sciatica, accompanied by radiating pain and numbness in the lower limbs. It is recommended that patients seek timely medical examination, clear causes for targeted treatment, pay attention to rest in life, avoid strenuous activities or overwork, and seek medical attention on time for maternity examination.