It is quite normal to have back pain at 35 weeks of pregnancy. This is because in the second trimester, with the rapid development of the fetus, pregnant women are easily deficient in various nutrients, as well as minerals, especially calcium, vitamins and iron. Once deficient, it will easily cause back pain and lumbago. When lumbago is accompanied by leg cramps and sciatica, in addition to quickly replenishing vitamin B1, you should also consult your doctor for help in a timely manner, and dietary supplements are recommended for mild deficiencies. In the later stages of pregnancy, with the further development of the fetus and the gradual entry of the fetus into the pelvis, it can also lead to the appearance of symptoms such as back pain. On the other hand, it should also be noted that preterm babies appear to signal early entry into the pelvis by means of lumbar soreness and back pain. Therefore, in late pregnancy, if there is severe lumbar soreness and back pain, it may also be a symptom of preterm labor, and if the pain is unbearable, it is recommended to go to the hospital for examination in time.