During pregnancy, pain in the thighs is considered to be caused by an enlarged fetus pressing on the inferior vena cava and obstructing blood flow. After pregnancy, the uterus becomes right-sided and presses on the abdominal aorta, resulting in poor blood circulation, causing pain in the thigh root or sciatic nerve pain. If the pain is more serious, you can do massage therapy, which can promote blood circulation and relieve pain. If the thigh pain is more serious, it may also be caused by a lack of calcium, because during pregnancy, the fetus grows faster, and if there is a lack of calcium, it can lead to bone pain, or leg cramps.