The common reasons for leg cramps during sleep at night in the sixth month of pregnancy are as follows: firstly, calcium supplements are not taken in time during pregnancy, both pregnant women and fetuses need calcium ions in the blood to meet their needs, and fetuses need calcium ions in a large amount during development, so it will lead to a serious shortage of calcium ions in the blood circulation of pregnant women and leg cramps; secondly, the uterus will be significantly larger and heavier during the larger months of pregnancy, Secondly, the uterus will be significantly larger and heavier in the older months of pregnancy, and at the same time the venous return of the lower limbs will be blocked due to the compression of the veins of the lower limbs, resulting in untimely and insufficient exchange of nutrients and substances between the muscles and the blood circulation, resulting in a lack of calcium ions in the muscles and finally leading to cramps in the legs.