Pregnancy puts extra strain on your veins, the vessels that carry the blood back to your heart. The muscular walls of your blood vessels relax during pregnancy, causing blood to pool and the vessels to swell, while the pressure on veins increases. A vein that is unusually swollen is called a varicose vein. Varicose veins are most common on the legs and calves, but they also occur around the vagina.
Compression stockings may relieve symptoms because they facilitate blood circulation in the body. You can also prevent swelling and make your legs feel lighter by regularly putting your legs up on a chair or a pillow on the couch. Some varicose veins completely disappear after pregnancy.
Source: - Lärobok för barnmorskor. Faxelid, E. Course literature 2001. - Myles Textbook for Midwives. Fraser, D. och Cooper, M. Churchill Livingstone 2003.