A functional ovarian cyst sometimes develops during the latter part of the menstrual cycle, when an egg follicle fills up with fluid. Factors that may increase your risk for developing a functional ovarian cyst include:

• A history of a previous functional ovarian cyst.
• Current use of clomiphene citrate, such as Clomid or Serophene, to start ovulation. For more information, see the topic Fertility Problems.
• Use of low dose progestin-only contraception (such as some implants, pills, and IUDs).

Tubal sterilization ("having your tubes tied") may increase the risk of functional ovarian cysts.² Further research is necessary to confirm this link.