Varicose veins are dilated and tortuous vessels which arise because the pressure of blood in the veins is higher than they are designed to withstand. They commonly affect the lower leg because the pressure in the veins deep in the leg is transmitted to superficial veins on the surface of the skin. There are valves between the superficial veins and the deep veins which are designed to prevent blood passing back from the deep veins to those on the surface. The uterus presses on the deep vessels draining the legs, so that the pressure increases and the valves fail to work. Resting with the legs elevated, and the proper use of support stockings will help prevent the development of varicose veins. Similar veins can also develop over the vulva where their discomfort might be eased by the use of supportive underwear.