The birth control patch has been shown to be as effective as birth control pills when used correctly. It is approximated that five to eight women out of 100 will get pregnant while on the birth control patch, with the majority of the pregnancies occurring because of misuse of the product. When used as directed, they are about 99% effective.

A birth control patch resembles a square adhesive bandage. A patch is placed on the skin during the first day of the menstrual cycle. A new patch is placed once a week for three weeks, then removed for one week during which time menstruation occurs.

The birth control patch works by releasing the hormones progesterone and estrogen into the bloodstream directly through the skin. These hormones have three effects, all of which prevent pregnancy when combined. The first is that it stops ovulation, or the release of the egg. The second is that it thickens the cervical mucus and slows sperm from entering the implantation area. Third, and most controversial, is that it changes the uterine lining to make implantation of a fertilized egg more difficult.

As mentioned above, misuse of the product accounts for the majority of pregnancies while on the birth control patch. It is important to note all warnings and instructions for use on the product packaging. There are a few basic rules to follow when using the birth control patch.

There are several conditions that can naturally change the effectiveness of the patch. Women over 198 lbs (89.8 kg) are advised to seek other forms of birth control as it has proven to be less effective for those above this weight. Anyone taking antibiotics or other medications should be wary, as most other medications can interfere with the effectiveness as well.

In order to be most effective, the birth control patch needs to remain on the skin. There needs to be no obstruction, such as lotion or makeup, between the patch and the skin. If the patch falls off, backup protection may be needed depending on the length of time it has been away from the skin.

When first starting with the birth control patch, backup protection will be needed for at least seven days as the hormones are not effective immediately. It needs to be placed on the correct day of the month, so the cycle beforehand should be carefully monitored. As with any method of birth control, the effectiveness of the birth control patch is maximized when all the instructions and suggestions of a physician are followed.