The most common line I hear from my clients is, “I just received my box of medications and I’m really overwhelmed.” And who can blame them! Not only are the physical contents overflowing but the medications seem scarier without an actual explanation of their purpose.

Fertility clinics often hand out an estimated timeline or schedule for injections but the medical indication is usually vague; something along the lines of, “they stimulate your eggs” or “they help you grow more eggs.” Neither of these is technically wrong – they do stimulate your eggs and help you grow more eggs – but I find the more educated my clients are the better they feel about the process and the more confident they are throughout.

The hormones used during egg retrieval cycles are synthetic versions of the ones already present in your body. As obvious as this may sound, many of my clients don’t actually know this. Here’s a chronological breakdown of the most frequently used hormones and their mechanism of action.

A stimulation cycle typically starts with both Gonal-F or Follistim and Menopur. Gonal F and Follistim are the two different FSH (follicle stimulating hormone) pens. Menopur is a combination of FSH and LH (luteinizing hormone) and requires mixing. These are meant to spur follicle development which is quantified with both the actual growth in size (in millimeters) of the follicles as well as a rising estrogen level. Your body naturally wants to grow and ovulate only 1 follicle per cycle. Increased amounts of FSH and LH push your body to produce more.

At some point during this type of protocol, which is the most common, a third medication is added – either Cetrotide or Ganirelix. These are the two different “antagonist”  medications meaning they block the action of GnRH (human gonadotropin releasing hormone). The purpose of the antagonist is to keep the follicles growing together in a cohort rather than your body pushing for 1 to go off from the rest and ovulate on its own. They can be used during the stimulation part of the cycle like this or in some protocols as part of the prep for a stimulation cycle. When used in prep for a stimulation cycle their purpose is to prime the receptors for FSH and LH so they hopefully bind better and therefore illicit a higher response from your ovaries.

So we have your pen and your Menopur stimulating actual follicle production and growth and your antagonist keeping this growth in tandem. Once we see the follicles in an appropriate size range that indicates maturity you’re ready to be triggered for ovulation and your egg retrieval procedure. The medications used as “triggers” are hCG (human chorionic gonadotropin) and Lupron (leuprolide acetate), which is a strong version of GnRH. hCG can come in different forms, such as Ovidrel, and as different brand names, such as Pregnyl & Novarel. (To note, Lupron can also be used during some stimulation protocols as well.) These can be used alone or together, which would then be called a dual trigger, to trigger ovulation and the release of your follicles for retrieval.

As for the embryo transfer cycle, the 2 most commonly used medications are Estrace (estradiol), which is a synthetic version of estrogen, and progesterone, which can come in different forms – oral tablets, vaginal suppositories or intramuscular injection. Estrogen can also be done via patches, a vaginal insertion or intramuscular injection. Estrogen is introduced at the beginning of the cycle to start thickening your endometrial lining and progesterone is introduced a given number of days prior to the actual embryo transfer to mimic your body’s natural ovulation cycle.