There is a suggestion that the birth-control patch, Ortho Evra may increase the risk of blood clots moreso than the pill. Normally, the risk ratios for thromboembolism in women taking OCs compared with women who did not take an OC ranged from 1.1 to 4.8 (depending upon the type of study). However, some are saying the patch further increases this risk:

If you are a woman taking the pill who doesn't smoke and is under 35, the chance that you are going to have a blood clot that doesn't kill you is between 1 and 3 in 10,000. Your risk of dying from a blood clot while using the pill is about 1 in 200,000.

By contrast, with the patch, the rate of nonfatal blood clots was about 12 out of 10,000 users during the clinical trials, while the rate of deaths appears to be 3 out of 200,000.

It would be wise to wait until more data comes out. However, if one is already at higher risk for a clot (i.e. age > 35, smoking, obesity), I would certainly be wary of the patch. (Medoza, "Birth-Control Patch May Have Higher Risk", AP/ABC News, Jul.16)