Subscribe to the BioNews newsletter for free

Advanced Search

Search for

Like the Progress Educational Trust on Facebook

The Fertility Show, Manchester Central, 24-25 March 2018


Clomiphene outperforms new treatment for unexplained fertility

28 September 2015

By Arit Udoh

Appeared in BioNews 821

A study shows that treatment of unexplained infertility with the standard treatment clomiphene results in more live births, and a lower risk of multiple births, than a potential new drug letrozole.

The research, called the Assessment of Multiple Intrauterine Gestations for Ovarian Stimulation (AMIGOS) trial, compared three drugs that stimulate the ovaries to produce an egg – clomiphene, gonadotropin and letrozole.

Women in the trial – aged 18 to 40 years – received either injectable gonadotropin, or clomiphene or letrozole administered orally. Ovarian stimulation was followed by intrauterine insemination in 900 couples with unexplained infertility for up to four cycles.

The study authors report in the NEJM that the rate of clinical pregnancies, as assessed by the presence of fetal heartbeat, was significantly higher in the gonadotropin and clomiphene groups (35.5 and 28.3 percent, respectively) than in the letrozole treatment group (22.4 percent). Live birth rates were also significantly higher at 32.2 and 23.3 percent with gonadotropin and clomiphene, respectively, compared to 18.7 percent in the letrozole group.

The rate of multiple pregnancies was also lower in the clomiphene group at 9.4 percent compared to 13.4 percent with letrozole therapy. And multiple pregnancy rates were highest in the gonadotropin group (31.8 percent). All the live-birth multiple pregnancies in the clomiphene and letrozole group were twins compared to treatment with gonadotropin, which resulted in 25 twins and 6 triplets.

Ovarian stimulation using gonadotropin or clomiphene with intrauterine insemination is a standard treatment approach for unexplained infertility, the authors explain.

However, ovarian stimulation is frequently complicated by ovarian hyperstimulation syndrome and by multiple gestations, which leads to an increased risk of preterm birth and neonatal morbidity. It had been hoped that letrozole might overcome these issues by maintaining the live birth rate and lowering the multiple gestation rate.

The authors note that previous research showed that letrozole successfully stimulates ovulation in women with polycystic ovarian syndrome with no increased risk of multiple pregnancies.

However, co-author Dr Esther Eisenberg, from the Eunice Kennedy Shriver National Institute of Child Health and Human Development said they conclude that in unexplained infertility 'Letrozole treatment offered no advantages over clomiphene treatment.'

NEJM | 24 September 2015
Medscape | 24 September 2015
National Institutes of Health (press release) | 23 September 2015
CBS News | 24 September 2015


11 July 2016 - by Dr Lanay Griessner 
A little-known virus has been found in the uteruses of around half of women with unexplained infertility, a study has found...

13 July 2015 - by Professor Roy Homburg and Dr Gulam Bahadur 
The recommendation in the 2013 NICE guideline to exclude IUI as a treatment option is based on flimsy, and sometimes mistakenly interpreted, evidence...
26 January 2015 - by Dr Kimberley Bryon-Dodd 
A US study has found that despite increased use of ICSI over recent years, the technique is not associated with any improved reproductive outcomes over conventional IVF...
11 November 2013 - by Dr Steven Fleming 
Despite the views of several IVF experts that intra-cytoplasmic sperm injection is overused in IVF, it continues unabated. So why is nobody listening?...
05 December 2011 - by Dr Caroline Hirst 
Women receiving fertility treatment are more likely to become pregnant if they take multivitamin supplements, reports a UK pilot study...
23 October 2007 - by MacKenna Roberts 
By MacKenna Roberts: New research found that hormone injections to achieve pregnancy do not 'provide any added benefit' financially or medically in women under 40 as an alternative infertility treatment before advancing to IVF, announced head researcher Dr Richard Reindollar, from the Dartmouth-Hitchcock Medical Centre in New Hampshire, last week...

Be the first to have your say.

You need to or  to add comments.

By posting a comment you agree to abide by the BioNews terms and conditions

- click here to enquire about using this story.

Published by the Progress Educational Trust
Advertise your products and services HERE - click for further details

Good Fundraising Code

Become a Friend of PET HERE and give the Progress Educational Trust a regular donation