Pregnant five and a half months right lumbar pain is common for the following reasons: First, lumbar muscle strain, after pregnancy, weight increased significantly, and the center of gravity of the body shifted forward, at this time the lumbar spine muscles will be loaded, while pregnant women sit in a poor posture for a long time, but also can be caused by the right lumbar muscle strain resulting in pain symptoms in the lumbar region. Just need to stay in bed for a few days, while localized hot compresses, pain symptoms can be relieved. Second, urinary stones, such as kidney stones and ureteral stones, after pregnancy, daily activities to reduce, such as water consumption is also reduced, can form stones in the urinary system, stone stimulation of the renal pelvis and ureter can cause the right side of the waist pain symptoms. Urine routine examination can show increased white blood cells and red blood cells, and ultrasound examination of the urinary system can also make a clear diagnosis. Treatment can increase the daily water intake and moderate activity, which can promote the discharge of stones from the body.