Nine weeks of pregnancy back pain may be uterine enlargement, lumbar disc herniation, miscarriage, etc., the patient should consult a doctor in a timely manner to clarify the cause of the disease and then carry out appropriate treatment. 1. Uterine enlargement: During pregnancy, as the gestation month increases, the fetus is gradually growing, the uterus will also be regularly enlarged, the patient may have back pain, frequent urination and other symptoms, such people should pay attention to rest, avoid overwork, generally no special treatment. 2. Lumbar disc herniation: patients with lumbar disc prolapse during pregnancy may have symptoms such as lumbago, radiating pain in the lower limbs, and numbness, etc. Such people should pay attention to rest, and can carry out local massage, physiotherapy, and if necessary, surgery. 3. Pre-eclampsia: If the 9 weeks of pregnancy back pain and accompanied by a small amount of vaginal bleeding, should be considered to be caused by pre-eclampsia, this group of people should pay attention to rest, prohibit sex, if necessary, the use of dextroprogesterone, progesterone and other drugs for treatment. The use of specific drugs need to be under the guidance of the doctor.