The symptoms of cramps in the calves of pregnant women while sleeping and stretching are mainly considered two factors: first, with the gradual increase of the fetal uterus, the lumbar load of pregnant women also gradually increases, coupled with changes in the hormone levels of pregnant women themselves, resulting in ligamentous laxity around the lumbar spine, thus generating instability of the lumbar spine, and after the activity of the lumbar spine due to the instability of the lumbar spine repeatedly appears slight activity, thus stimulating the corresponding nerve roots, resulting in Mild inflammatory reaction or mild ischemic changes occur locally. The nerve roots of the lower limbs will be stretched when stretching, and in the presence of the existing slight pathological base changes, the strain will lead to the dysfunction of the sciatic nerve in the lower limbs, which will lead to the dysfunction of the calf muscles controlled by the sciatic nerve, resulting in the symptoms of cramps. Second, consider that because of the growth of the uterus and the fetus, it will cause some compression of the abdominal organs, and even compression of the main veins of the lower limb return, namely the inferior vena cava, which will lead to poor blood return to the lower limbs, and the lack of muscle compression of the lower limbs during sleep, which makes the return flow poor, resulting in the performance of relative bruising of the lower limbs, blood stasis, and the accumulation of local metabolites This can easily lead to muscle dysfunction in the lower leg and produce cramping symptoms.