GnRH Analogues – Indications & Use

By BSc, MSc (embryologist) and BA, MA (fertility counselor).
Last Update: 07/10/2014

GnRH analogues are used in the main Assisted Reproductive Technologies (ART), such as AI, IVF, and ICSI. These drugs are used to prevent early follicular luteinization and to regulate the date of ovulation so that it does not occur prematurely.

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


The main effects of GnRH analogues are:

  • Quick release of gonadotropins: the binding between the GnRH analogue and its receptor provokes an immediate release of the FSH (follicle-stimulant hormone) and LH (luteal hormone) hormones.
  • Temporary blockage of gonadotropins release: this occurs in the hypophysis because the stock of FSH and LH is empty, preventing the hypophysis to communicate with the ovary, a process that would have an effect on ovulation. It takes place 5 to 10 days after its first administration.

These two effects are enough the synchronize the follicles recruited by the ovary, favoring an homogeneous follicular growth and lowering the variability of the ovarian response.


The prescription of GnRH analogues is especially indicated in the following situations:

  • In women who have had low quality oocytes during past cycles. Early LH peaks are prevented. Early LH peaks provoke early follicle luteinization, and that leads to poor oocyte quality.
  • Women with polycystic ovary syndrome (PCOS) and elevated basal blood LH levels.
  • Women with polycystic ovary syndrome (PCOS) and a high blood androgens levels.


The main advantages of the administration of GnRH for ovulation stimulation are:

  • Lower cancellation rates.
  • LH levels, responsible for ovulation, will decrease.
  • Follicle growth is quite homogeneous, lowering the variability of the response.
  • High amount of oocytes obtained from the ovarian puncture, the number of grown eggs to be fertilized increases as well as the number of embryos that can be obtained in every menstrual cycle.
  • A sharp increase occurs in pregnancy rates probably due to the local effect that GnRH analogues produce on the ovaries and the endometrium.


The disadvantages of using GnRH for ovarian stimulation in the assisted reproduction cycles are:

  • The risk of having ovarian hyperstimulation syndrome increases due to the flare-up effect.
  • Insufficiency in the luteal body is more likely to happen; therefore, in order to have the endometrium ready to receive the embryos, it is necessary to administer another hormone called progesterone so that the endometrium thickens.
  • It may lead to the formation of ovarian cysts.
  • Greater chances of having a multiple pregnancy with all the risks associated with this kind of pregnancy.

GnRH drugs commonly prescribed in assisted reproduction treatments are: Decapeptyl, Synarel, and Procrin.

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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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