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Posted by on Dec 22, 2017 in Infertility | 0 comments

In a nutshell

This study reviewed the use of clomiphene citrate and letrozole during in vitro fertilization treatment.

Some background

Assisted reproductive treatment (ART) involves a number of steps. In vitro fertilization (IVF) is a procedure where embryos are fertilized outside of the womb. In order to perform IVF, a woman may undergo controlled ovarian hyperstimulation (COH). This involves administering medications called gonadotrophins that cause multiple oocytes (eggs) to be released. They are then harvested and undergo IVF.

Some women may respond poorly to gonadotrophins and other medications are then co-administered to improve the oocyte harvest. Clomiphene citrate (CC)) and letrozole are two such drugs.

Methods & findings

This study reviewed the use of clomiphene citrate (CC) and letrozole in IVF treatment.

CC works by mimicking the effects of estrogen, and facilitates the release of the body’s own gonadotrophins. This means that a patient being treated with CC will require a lower dose of gonadotrophin medication.  Using CC and a low dose of gonadotrophin is a mild stimulation protocol that will yield less than 8 oocytes and reduce the risk of ovarian hyperstimulation syndrome (OHSS). Two studies have shown that a mild stimulation protocol using CC results in similar success of clinical pregnancy as the standard protocol. There was a lower incidence of OHSS in patients in the mild stimulation group.

Letrozole works by blocking an enzyme that controls estrogen production, facilitating the release of the body’s gonadotrophins. Some studies have shown letrozole is safe and effective for IVF treatment, especially for patients with breast cancer. Letrozole has also been shown to be effective in poor responders to conventional COH. To date, letrozole has not been administered to normal responders but it may be useful for these patients. It may also be suitable for patients with endometriosis, as letrozole can increase the expression of a protein called integrin. Integrins are reduced in patients with endometriosis and is associated with poor IVF outcomes. 

The bottom line

This study reviewed the use of clomiphene citrate and letrozole during in vitro fertilization treatment.

The fine print

Further studies are needed to investigate the suitability of letrozole in normal responders. 

What’s next?

If you have any concerns regarding IVF treatment, please discuss with your doctor. 

Published By :

Fertility and Sterility

Date :

Oct 01, 2017

Original Title :

In vitro fertilization treatments with the use of clomiphene citrate or letrozole.

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