The birth control pill works in a few different ways to prevent pregnancy. It stops ovulation by shutting down the communication between the brain and the ovary. It often changes the cervical mucus making it difficult for the sperm to swim through and up into the uterus. And some birth control pills alter the lining of the uterus making implantation impossible.
If taken regularly as directed, the pill has a 99 percent pregnancy protection rate which is why so many women choose this route for a birth control method. However, there are three other beneficial reasons that the pill may be warranted.
1) Those women who experience painful ovarian cysts may benefit from the main action of the pill. Because it prevents ovulation, a follicle with an egg inside will not form, and therefore will not go on to develop into a cyst.
While most cysts are small, harmless, and dissolve on their own, some can grow quite large, causing quite a bit of pain and/or abdominal bloating. They might even require surgery to be removed.
2) The consistency of the pill can alleviate menstrual migraines for those women who suffer each and every month. One of the theories behind these types of headaches is that the change in hormones close to the onset of menses and through bleeding is the reason for the head pain.
Some women have migraines that are so severe that they become non-functional and require serious medication. As a result, the birth control pill provides a controlled state of hormones throughout the entire month. This can often alleviate those intense hormonal swings that might otherwise result in a migraine.
Take note though. Those women whose migraines come with an aura (a telltale early sign that the pain is coming such as a change in vision) are advised against taking the pill.
3) The American Cancer Society reports that women who are on the pill for five years or more have a 50 percent lower risk of developing ovarian cancer. 
1) American Cancer Society. (2016). Can ovarian cancer be prevented? Retrieved on May 25, 2016.
2) MacGregor, E. (2009). Menstrual Migraines: Therapeutic Approaches. Retrieved on May 25, 2016.
3) NHS. Combined Pill. (2016). Retrieved on May 25, 2016.
4) Office on Women’s Health. US Department of Health and Human Services. (2014). Ovarian Cysts. Retrieved on May 25, 2016 .