USA. According to the US FDA, a weekly contraceptive skin patch (Ortho Evra) that releases ethinyl estradiol (an estrogen hormone) and norelgestromin (a progestin hormone), exposes women to higher levels of estrogen than most birth control pills. Since the patch is changed once a week, it decreases the risk of pregnancy associated with the typical birth control pills when a woman might miss one or more daily doses. However, this advantage should be considered in the light of the risks due to exposure to a higher level of estrogen with the patch. Women are advised to talk to their physician to see if the patch is the right birth control option for them.

Reference:

FDA News. United States Food and Drug Administration, 10 November 2005 (http://www.fda.gov).