Ovarian cysts are fluid-filled sacs that develop on or within the ovaries, commonly found in women of reproductive age. Hormonal contraception (HC), such as the combination birth control pill, is widely prescribed for fertility control and various gynecological conditions. The relationship between HC and ovarian cysts is often misunderstood, leading many to wonder if this medication can reliably stop cysts from forming.
Understanding Different Types of Ovarian Cysts
Ovarian cysts are broadly categorized based on their origin, which determines how hormonal contraception affects them. The most frequent type is the functional cyst, which arises directly from the normal monthly ovulatory process. These cysts are not considered pathological, as they result from a slight deviation in the menstrual cycle’s hormone-driven sequence of events.
Functional cysts include follicular cysts and corpus luteum cysts. A follicular cyst forms when the follicle fails to rupture and release the egg, continuing instead to fill with fluid. A corpus luteum cyst occurs after the egg is released, when the remaining structure fills with fluid or blood rather than dissolving. Most functional cysts are benign and typically resolve spontaneously within one to three menstrual cycles.
Pathological cysts, by contrast, are not related to the normal ovulatory cycle and result from abnormal cell growth. Examples include dermoid cysts, cystadenomas, and endometriomas (often called “chocolate cysts”). Since these types of cysts are not a byproduct of normal ovulation, hormonal contraception does not prevent their initial formation.
How Hormonal Contraception Stops New Cysts
Combined hormonal contraceptives (CHCs), which contain synthetic estrogen and progestin, are highly effective at preventing the formation of new functional ovarian cysts. This preventive action is directly linked to the medication’s primary mechanism for preventing pregnancy: suppressing ovulation. The synthetic hormones provide a steady level of hormones that the body interprets as sufficient, thereby creating a negative feedback loop.
This feedback loop acts on the pituitary gland, suppressing the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The suppression of FSH prevents the development and maturation of ovarian follicles, which are the precursors to functional cysts. The suppression of LH also prevents the luteinizing hormone surge, which is the hormonal signal required to trigger the final release of the egg.
By blocking the release of FSH and the LH surge, CHCs effectively induce anovulation, meaning no egg is released. Since functional cysts result directly from the ovulatory process, eliminating ovulation eliminates the opportunity for these specific cysts to form. Studies show that women using CHCs experience a significant reduction in the development of new functional cysts compared to those who do not.
Managing Existing Cysts with Birth Control
While hormonal contraception (HC) prevents new functional cysts, its role in managing existing cysts is distinctly different. Historically, combined oral contraceptives were prescribed to treat existing functional cysts, based on the belief that suppressing hormones would hasten their resolution. However, recent meta-analyses have demonstrated that HC does not cause existing functional cysts to shrink or disappear any faster than simply observing them.
Existing functional cysts typically resolve on their own through a process called expectant management. HC is therefore not considered a treatment to accelerate the disappearance of a pre-existing functional cyst. Instead, HC is often utilized to manage symptoms associated with ovarian cysts, such as irregular or painful bleeding, by regulating the menstrual cycle.
For pathological cysts, like endometriomas, HC helps manage the underlying condition, endometriosis, by reducing the hormonal stimulation of the misplaced tissue. While the medication may help control the progression of endometriosis and reduce pain, it generally does not eliminate the endometrioma itself.