Subscribe to the BioNews newsletter for free

Advanced Search

Search for

Like the Progress Educational Trust on Facebook



Frozen embryos increase pregnancy success for mothers with PCOS

15 August 2016

By Dr Barbara Kramarz

Appeared in BioNews 864

Women with polycystic ovary syndrome (PCOS) who undergo IVF using frozen embryos are more likely to have successful pregnancies than those using fresh embryos, a study suggests. 

Those using frozen embryos had fewer pregnancy losses than those using fresh embryos (22 vs. 32.7 percent), more live births (49.3 vs. 42 percent), and the newborns had higher birth weights. There was also a reduction in the risk of ovarian hyperstimulation syndrome (OHSS), from 7.1 to 1.3 percent.

'Women with PCOS may have a higher chance of a successful pregnancy, and may have less ovarian hyperstimulation, when you electively freeze all the embryos and perform a frozen embryo transfer than if you do a fresh transfer,' said Professor Richard Legro of Penn State College of Medicine, one of the authors of the study, which was published in the New England Journal of Medicine.

'This protocol potentially offers immediate benefits to women with PCOS, so practitioners should consider freezing all embryos for these patients.'

Women with PCOS are at a higher risk of developing OHSS, a potentially life-threatening condition that can result from IVF treatment, so researchers had been looking at ways to reduce this risk. The study, led by Professor Zi-Jiang Chen of Shandong University, involved 1508 Chinese women with PCOS, who were randomly assigned to either receive fresh or frozen embryos.

The researchers suggest that allowing the ovaries and endometrium to recover after hormonal stimulation may be the reason for the improved outcomes. 'By electing to freeze all the embryos, you create a healthy environment for the best embryos, as opposed to putting them back in a disturbed environment,' explained Professor Legro.

Although there were fewer pregnancy losses in the frozen embryo group, there were two stillbirths and five neonatal deaths in this group, whereas there were none in the fresh embryo group. These differences could have been by chance. 'It's a small red flag and something that does require further investigation,' Dr Owen Davis from the Center for Reproductive Medicine at Cornell Medical College, who was not involved in the study, told the Los Angeles Times.

There was also a higher rate of pre-eclampsia in the women who received frozen embryos, although no women developed severe pre-eclampsia, which is life threatening.

In an accompanying editorial, Professor Christos Coutifaris of the University of Pennsylvania, who was not involved in the study, pointed out that using frozen embryos increases the costs of treatment by a factor of five to ten, and there is also an 'emotional cost' of deferring the embryo transfer by several weeks. But he concluded that 'in high-risk women, such as those with the PCOS, a freeze-only approach to minimise the risk of the OHSS may outweigh the costs'.

New England Journal of Medicine (editorial) | 11 August 2016
The New England Journal of Medicine | 11 August 2016
Eurekalert (press release) | 10 August 2016
The LA Times | 10 August 2016


06 November 2017 - by Helen Robertson 
Using just one embryo during IVF results in a much higher chance of a healthy pregnancy and birth, according to a study presented at the annual meeting of the American Society for Reproductive Medicine...
09 January 2017 - by Ayala Ochert 
Implanting two embryos can reduce IVF success by a quarter if one of the embryos is of poorer quality, new research suggests...
05 December 2016 - by Dr Geeta Nargund 
There has been a 40 percent rise in hospital admissions with severe OHSS in UK fertility clinics in 2015. This extraordinary statistic reveals that the time has now come for firm action to reverse the trend of severe OHSS, a serious but preventable condition...
30 September 2016 - by Dr Linda Wijlaars 
Twelve families in South Australia have lost embryos after a power outage compromised the incubators that the embryos were being stored in...
30 August 2016 - by Dr Bruce Shapiro 
Is it better to transfer fresh embryos during IVF or frozen embryos that have been thawed...

17 August 2015 - by Meghna Kataria 
Using frozen donated eggs over fresh ones for IVF hampers the odds of a successful live birth, a study has found...
28 July 2014 - by Purvi Shah 
Twelve healthy babies have been born after trials of a hormone treatment called kisspeptin-54 that has been hailed as a safer way to mature women's eggs prior to IVF...
10 September 2012 - by Dr Gabrielle Samuel 
Women who undergo fertility treatment using cryopreserved embryos may have healthier babies and fewer complications than those who use 'fresh' embryos, a study suggests....
09 January 2012 - by Dr Rosie Gilchrist 
A new study has shown that babies born following IVF using frozen embryos may be born later and weigh more than babies born from fresh embryos....

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


Public Conference
8 December 2017

Speakers include

Professor Azim Surani

Professor Magdalena Zernicka-Goetz

Professor Robin Lovell-Badge

Sally Cheshire

Professor Guido Pennings

Katherine Littler

Professor Allan Pacey

Dr Sue Avery

Professor Richard Anderson

Dr Elizabeth Garner

Dr Andy Greenfield

Dr Anna Smajdor

Dr Henry Malter

Vivienne Parry

Dr Helen O'Neill

Dr César Palacios-González

Philippa Taylor

Fiona Fox

Sarah Norcross

Sandy Starr


Good Fundraising Code

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