Pain; 3, calcium deficiency: in the process of pregnancy, the fetus needs a lot of calcium, pregnant women’s calcium consumption is very large, leading to the phenomenon of calcium deficiency in pregnant women, causing the symptoms of lumbar pain, the need for timely supplementation of calcium; 4, hydronephrosis: due to the uterus enlargement, the compression of the right side of the ureter leads to the right side of the kidney hydronephrosis, resulting in pain in the lower back, which needs timely treatment. 7 months pregnant women are more special, do not recommend random use of drugs to relieve pain. You can do some gentle and soothing exercises, such as walking and yoga for pregnant women. If the pain does not improve and affects the daily life of the pregnant woman, go to the hospital in time and choose a reasonable way to relieve back pain.