Many clinics prescribe birth control pills for 10 to 21 days before starting a fertility treatment cycle, like IVF, egg freezing, or embryo transfer. The common first thought is, “why would I take birth control if I am trying to get pregnant?!” There are two main reasons why clinics use birth control while preparing for a treatment cycle: suppression and scheduling.
It seems counterintuitive to suppress your hormones and ovaries with birth control right before you start stimulating them to grow lots of eggs, but the truth is that suppression before starting can be a good thing! The goal of treatment is to stimulate the growth of many follicles simultaneously, and this can’t happen if you have what’s called a dominant follicle. The suppression that birth control provides prevents the body from growing a dominant follicle and ovulating in the few weeks prior to treatment. This is useful because it keeps all of the follicles in the ovaries immature and around the same size. That way, when the birth control is stopped and the ovarian stimulation medications are started, the follicles will all be able to respond in a more synchronized manner.
A follicle is a tiny fluid-filled sac in the ovary that contains an egg. In a normal menstrual cycle, your body selects one follicle to grow and mature before the others, it is known as the dominant follicle.The dominant follicle contains the egg that will be ovulated that month. Once a dominant follicle is selected, the other follicles in the ovaries do not grow and also won’t respond to the medications taken during ovarian stimulation.
Suppression can also be useful for people who are prone to simple ovarian cysts. Simple cysts are created when the remnants of the previous cycle’s dominant follicle (corpus luteum) do not resolve at the end of the cycle as they normally would. These cysts can produce hormones and interfere with the body’s natural menstrual cycle and ability to respond to fertility medications. When birth control suppresses the ovaries and prevents ovulation from occurring, the likelihood of one of these simple cysts interfering with the start of a treatment cycle is greatly decreased.
Because of the suppression that birth control provides, starting birth control before your treatment cycle can provide some flexibility in start dates. When birth control isn’t used in preparing for treatment, then the treatment usually starts on the second or third day of your period. This means that you are tied to the schedule of your menstrual cycle. Therefore, you can’t easily work around work, travel, or event schedules. It also means the clinic can’t manipulate the start dates of patients to provide a more even and consistent flow of patients.
Clinics can use birth control to balance their schedules for patients starting treatment. This can provide better patient experience due to appropriate staffing for patient load, more time for the care team and doctor to spend with each patient, and more available appointment dates and times.
Many clinics use birth control prior to starting fertility treatment cycles. If you have questions about your protocol and the use of birth control, you can always reach out to your doctor or care team to discuss your protocol and instructions.