Two new studies provide specific information about which pills cause the highest and lowest risks of deep vein thrombosis. The first study looked mainly at pill composition. The second study looked at risk relative to regimen, estrogen dose, type of progestogen, and route of administration. ...this information is a welcome addition. It turns out that more estrogen-->higher DVT risk. The type of synthetic progesterone also matters. The overall absolute risk for DVT (per 10,000 woman years) is 6.29 in current pill users and 3.01 in nonusers. "For women genetically predisposed to venous thrombosis who still want hormonal contraception, however, a progestogen only pill or hormone releasing intrauterine device seems to be the appropriate first choice."

A FEW PROGESTOGENS AND RISK OF DVT
levonorgestrel: 4x more risk than not using the pill (safest of them all)
gestodene: 5.6x more risk
desogestrel: 7.3x
cyproterone acetate: 6.8x
drospirenone: 6.3x

http://www.medscape.com/viewarticle/707437?src=mpnews&spon=16&uac=89474MT

UPDATE 9/2010: Yaz causes 64% more clots.