In vitro fertilization (IVF) is a complex and highly coordinated process used to assist in conception, involving the fertilization of an egg outside the body. Individuals undergoing this treatment often begin by taking birth control pills, or oral contraceptives, which may seem counterintuitive when the goal is pregnancy. This preparatory phase is a standard component of many IVF protocols, designed to optimize the body’s response to subsequent fertility medications. The temporary use of these hormones allows the fertility team to establish a controlled environment for the ovarian stimulation phase that follows.
Suppressing Natural Hormonal Activity
The synthetic hormones within birth control pills—typically estrogen and progestin—work by temporarily quieting the body’s natural reproductive cycle. These hormones signal to the brain’s pituitary gland that enough reproductive hormones are present, pausing the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This suppression is a deliberate strategy in IVF preparation, ensuring that the ovaries are in a quiet, resting state before the intensive stimulation phase begins.
This suppression prevents the ovaries from naturally selecting and maturing a dominant follicle, which occurs in a typical menstrual cycle. Instead, the ovaries are prepared to respond uniformly to the high doses of gonadotropins introduced later. This allows the medical team to control the hormonal feedback loop, setting the stage for a more effective ovarian response and maximizing the number of eggs that will grow.
Achieving Uniform Follicle Synchronization
The primary purpose of using oral contraceptives before stimulation is to achieve follicle synchronization. In a natural menstrual cycle, multiple small sacs containing eggs, known as follicles, begin to grow, but only one typically becomes dominant and fully matures. The goal of an IVF cycle is to retrieve multiple mature eggs to increase the chances of creating viable embryos.
By temporarily suppressing the natural hormonal drivers, birth control pills ensure that all available follicles are at a similar, small size before the ovarian stimulation drugs begin. When the patient stops the birth control pills and starts the stimulating injectable medications, this synchronized group of follicles is prompted to grow together at the same rate. This uniform growth pattern is crucial, as it allows the retrieval procedure to capture a higher number of mature eggs, maximizing the yield from the cycle.
Preventing Premature Ovulation and Cysts
Beyond synchronization, birth control pills serve a preventative role by stabilizing the ovaries. This stabilization is important for avoiding two complications that could otherwise force a cycle delay or cancellation. One risk is the development of follicular cysts, which are fluid-filled sacs that can produce hormones interfering with the response to fertility medications. The hormones in the pill help prevent the formation of these new cysts, ensuring the ovaries are in optimal condition for stimulation.
The other major concern is premature ovulation, where the body naturally releases its eggs before the medical team can retrieve them. Birth control pills halt the natural LH surge that triggers ovulation, locking the eggs in place until the fertility specialists administer the final maturation injection, known as the trigger shot. By preventing the ovaries from spontaneously releasing eggs, the oral contraceptives ensure the timing of the egg retrieval procedure is fully controlled by the clinic.
Streamlining Treatment Scheduling
The use of oral contraceptives is also a practical tool for streamlining the complex logistics of IVF treatment for both the patient and the clinic. IVF cycles require precise timing for monitoring appointments, blood work, and the egg retrieval procedure itself. Birth control pills provide the medical team with the ability to precisely dictate when a patient’s menstrual cycle will begin.
This control allows the fertility clinic to manage its schedule efficiently, allocating staff, ultrasound rooms, and laboratory resources for a predictable number of procedures. For the patient, this predictability is equally beneficial, offering a firm start date for the cycle and allowing for better personal and professional planning. By controlling the timing of the period, the clinic can ensure the patient begins the stimulation phase on a day that aligns with the clinic’s operational capacity and the patient’s availability.