Use of GnRH Antagonists in Fertility Treatments

By BSc, MSc (embryologist) and BA, MA (fertility counselor).
Last Update: 04/29/2014

GnRH antagonists are used in assisted reproductive treatments such as conventional in vitro fertilisation or ICSI.

These drugs are used to avoid the premature luteinization of follicles and control the ovulation date so that it does not occur too early.

Below you have an index with the 5 points we are going to deal with in this article.


GnRH antagonists are used to trigger ovulation in assisted reproductive treatments such as AI, IVF, or ICSI.

Its administration may cause the following effects:

  • GnRH antagonists binds to the receptor, therefore GnRH cannot bind (competitive blockage). Receptors are placed in the surface of the pituitary gonadotropic cells.
  • It blocks the synthesis of gonadotropins (FSH and LH) by the hypophysis, since it blocks GnRH receptors.
  • They have an immediate onset of action.
  • It prevents the flare-up effect of GnRH agonists to occur.


Prescription of GnRH antagonists is indicated in the following cases:


The advantages of this medicine in assisted reproduction cycles are mentioned hereafter:

  • It causes the immediate cancellation of LH serum levels, preventing thus premature ovulation.
  • It implies a shorter duration of the ovulation induction treatment.
  • It is usually well tolerated by women. It has few side effects, since the stimulation process is not very aggressive.
  • A lower dose of FSH is administered.
  • It decreases the frequency of ovarian hyperstimulation syndrome (OHSS).
  • Woman's recovery of the pituitary function occurs faster, which means it will not affect new stimulation treatments in future cycles.
  • It does not cause follicle cysts, since it prevents the flare-up effect which GnRH agonists would cause.


The use of GnRH antagonists involves few disadvantages, since it is well tolerated by most women with virtually no contraindications mainly because the stimulation process is not very aggressive.

The only problem is that its pregnancy rate is slightly lower (between 3% up to 5% less) than that obtained by means of ovarian stimulation protocols, where GnRH analogues are used due to the effect of the antagonists on the endometrium, the Fallopian tubes, the follicle, and the oocyte.

Medicines containing GnRH antagonists which are typically prescribed in assisted reproductive treatments are Cetrotide and Orgalutran.

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 Neus Ferrando Gilabert
Neus Ferrando Gilabert
BSc, MSc
Bachelor's Degree in Biology from the University of Valencia (UV). Postgraduate Course in Biotechnology of Human Assisted Reproduction from the Miguel Hernández University of Elche (UMH). Experience managing Embryology and Andrology Labs at Centro Médico Manzanera (Logroño, Spain). More information about Neus Ferrando Gilabert
Adapted into english by:
 Sandra Fernández
Sandra Fernández
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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