The most likely cause of leg cramps in pregnant women is a calcium deficiency. Calcium ion is an important factor involved in the contraction of skeletal muscles, and when low blood calcium occurs, neuromuscular excitability increases, which can easily lead to skeletal muscles in the legs, tonic contraction or even spasms and cramps. Pregnant women are prone to hypocalcemia during pregnancy due to malnutrition. Other problems, such as cold stimulation, temporary lack of blood supply to local muscles, and muscle fatigue caused by prolonged standing and walking, can also lead to leg cramps. After the middle of pregnancy, you should pay attention to calcium supplementation and diet, do more outdoor activities, get more sunlight to promote calcium absorption and keep warm. You should not overexert yourself and massage to promote blood circulation in the local muscles.