Earlier this year, Lena Dunham was hospitalized to treat a ruptured ovarian cyst, unintentionally shedding light on an often ignored area of women's health. Although most cysts don't require that kind of medical attention, they're far more common than you might realize.Any person who ovulates will almost certainly get some kind of ovarian cyst at some point, but that's not always a problem. For instance, your eggs are normally released from your ovaries every month. But sometimes, instead of breaking open to release the egg, the follicle grows into a cyst that'll go away on its own in a few months."During the process of ovulating, people will have ovarian cysts develop, and they’re usually asymptomatic," says Wendy Chang, MD at the Southern California Reproductive Center . "But when they get larger and rupture, that’s when people will feel them."In those cases, the pain can be mild or knife-in-your-side sharp. And there are a bunch of different things that cause cysts. Here's everything you need to know about the causes of ovarian cysts — and what they mean for your health.