The Norelgestromin/Ethinyl Estradioltransdermal System or "Transdermal Patch", as it is sometimes called, is another form of the birth control products commonly found in the pill form. Like the Pill, it does not offer protection against HIV or other sexually transmittable diseases, and like the Pill it also functions to prevent or end a pregnancy in three ways. I quote from the product information:
"Combination oral contraceptives act by suppression of gonadotropins. Although the primary mechanism of this action is inhibition of ovulation, other alterations include changes in the cervical mucus (which increase the difficulty of sperm entry into the uterus) and the endometrium (which reduce the likelihood of implantation)."
This information and more is available through the Ortho-Novum website, http://www.orthoevra.com. You will need to look for the words "prescribing information" that are listed in gray, suggesting no linkage. Click on that line and an Acrobat Reader document will download which contains full pharmocological information on the Patch.
See Does the Birth Control Pill Cause Abortions? for more information