Most of the medications used in fertility treatment are versions of the body’s own hormones.

In the natural menstrual cycle: 

  • the brain controls the pituitary gland and
  • the pituitary gland controls the ovaries.
  • the follicles in the ovaries create hormones that then feed back to the brain and pituitary to keep the whole system in control.
  1. First the brain releases a hormone called Gonadotrophin Releasing Hormone (GnRH).
  2. Then GnRH makes the pituitary release a hormone called Follicle Stimulating Hormone (FSH).
  3. FSH makes the follicles grow and the follicles release Estradiol (often abbreviated to E2).
  4. When the brain and pituitary sense increasing levels of E2 they ease off the release of FSH.

Fertility treatments like clomiphene, IUI with ovarian stimulation and IVF speed up the natural cycle process. 

Your clinic team at FA will monitor the ovaries during the course of treatment using blood tests and ultrasound scans. 

Medications & Hormones

GnRH - Gonadotrophin Releasing Hormone (GnRH) - Releases FSH and LH from the pituitary gland.  

  • Medications - GnRH agonists: Buserelin, Lupron, Leuprolide, Lucrin, Zoladex, Synarel 
  • What it does: Modified version of the body’s own hormone. They initially stimulate the release of FSH just like GnRH, but then the body adapts and stops secreting its own GnRH. This is called ‘down regulation’.  By doing this, they prevent the LH surge. 
  • Medications: GnRH antagonists:  Cetrotide, Orgalutran
  • What it does: Modified version of the body’s own hormone. They block the body’s GnRH and therefore prevent the LH surge.

FSH - Follicle stimulating hormone (FSH) - Stimulates follicles in the ovary to grow.

  • Medications: Follicle stimulating hormone (FSH) - Gonal F, Puregon, Elonva, Menopur
  • What it does: Copy or modified version of the body’s own hormone, so they do the same thing.

Luteinising hormone (LH) - A surge of LH in the middle of the cycle triggers the final maturation of the egg and ovulation of the follicle(s) containing mature eggs. After ovulation it helps maintain progesterone secretion.

  • Medication:  Luteinising hormone (LH): Luveris
  • What it does: Copy of the body’s own hormone. Not used much because it is so expensive.

human Chorionic Gonadotrophin (hCG) - hCG is the main hormone made by the early embryo once it implants. It has a similar biological effect to LH. hCG is the hormone detected by pregnancy tests. 

  • Medication: human Chorionic Gonadotrophin (hCG) Ovidrel, Pregnyl
  • What it does: Ovidrel is a copy of the body’s own hormone; Pregnyl is purified from the urine of pregnant women. Mainly used instead of LH to trigger ovulation because it is more convenient and cost effective.

Estradiol (E2) - E2 is the main estrogen hormone made by developing follicles. It has many actions, including growing the lining of the uterus (called the endometrium).

  • Medication: Estradiol (E2) - Progynova, Estrofem, Climara
  • Copy of the body’s own hormone. Used in manufactured cycles.

Progesterone (P4) - P4 is the main hormone secreted by the follicle once it has released its egg. Its major action is to maintain the lining of the uterus so an embryo can implant and cause a pregnancy. 

  • Medication: Progesterone (P4): Utrogestan, Crinone, Gestone
  • Copy of the body’s own hormone. Used in manufactured cycle, and to support the uterus in IVF cycles.
Other Medications Used:

Clomiphene citrate (CC)

  • Medication:  Serophene
  • What it does: Blocks feedback by estradiol so the pituitary gland releases more FSH.

The contraceptive pill

  • Medication: Levlen ED, Microgynon, Ava
  • What it does: Low dose estrogen in the pill stops the release of FSH and LH and helps make IVF more reliable.


  • Medication: Letara, Letrole
  • What it does: Blocks production of Estradiol so pituitary gland releases more FSH. – use the ‘search’ box to find the data sheet for any medication.