Many women use contraceptive methods that involve the hormones estrogen and progestin, which prevent the ovaries from developing and releasing mature eggs. This, therefore, prevents conception. Currently there are two well established types of birth control on the market. These possibilities are the pill form where the user ingests a large dose once a day for 21 days or the birth control patch is placed on the skin every week for three weeks out of the month. Women can also receive hormone shots or implants that last for four months. However, these methods only allow a menstrual cycle every four months, so they are difficult to compare to the other methods. All of these other methods can cause side effects such as headaches, blood clots, nausea, and breakthrough bleeding. However, there is a new form of birth control that comes in a flexible thin ring that is inserted into the vagina below the cervix. This ring is designed to releases a continuous low dose of hormone that is absorbed by the vagina and distributed into the blood stream. The ring actually releases two derivatives of estrogen and progestin known as etonogestrel and ethinyl estradiol (Organon USA Inc. 2005). See Figure 1 for the chemical structures of both of these compounds. Because the ring is only changed once a month, it ceases the fluctuation of hormone levels that is normal in the other birth control methods.