Stopping Ortho Evra
According to Planned Parenthood, a woman can get pregnant as soon as she stops using Ortho Evra. Because the patch releases a steady stream of hormones all week long until it is replaced by a new patch, a woman can theoretically become pregnant as soon as the patch is removed if another one does not replace it. The hormones may linger in the system a bit, however, which may mean that they will need to disappear from the body before the normal odds of conceiving return. This should not take more than approximately 24 hours.
Change in Cycle
One benefit of birth-control methods such as the patch or pill is that they regulate a woman's menstrual cycle. Like the pill, the patch works on a three-week cycle during which a daily dose of hormones is administered to the body. During the fourth week of the month, the patch is removed and the woman menstruates. However, once the patch is stopped it may take up to two months for a woman's menstrual cycle to return to the way it was before starting the patch. This can result in missed or irregular periods, which can make it difficult for a woman to predict when she will be menstruating and ovulating, thus making it more difficult to become pregnant.
The makers of Ortho Evra recommend that women consult their physicians before removing the patch if they are planning to become pregnant. There is also a slight chance--approximately 1 in 100--that a woman can become pregnant even while properly wearing the patch. There is also an increased chance of becoming pregnant if a woman fails to remove and old patch and reapply a new patch at the right time. She can also become pregnant if the patch falls off or if she takes certain medications or vitamins that can interfere with the patch's effectiveness, including St. John's wort, rifampin and certain medications used to treat seizures, HIV and yeast infections.