What causes leg cramps in the third trimester of pregnancy?

The main causes of leg cramps in the third trimester of pregnancy are as follows: 1. Calcium deficiency: In late pregnancy, the fetus grows rapidly and has an increased demand for calcium. If the pregnant woman fails to supplement sufficient calcium, it may lead to calcium deficiency, resulting in leg cramps. 2. Overexertion: Prolonged standing, walking, or other physical activities can overwork the calf muscles, causing muscle cramps. 3. Cold exposure: Failure to keep warm may expose the calves to cold stimuli, leading to poor local blood circulation and triggering cramps. 4. Lower limb varicose veins: In late pregnancy, the enlarged uterus may compress the inferior vena cava, obstructing venous return in the lower limbs, which could lead to varicose veins and subsequently cause calf cramps.