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Ovarian stimulation linked to egg abnormalities in older mothers

04 July 2011

By Dr Lux Fatimathas

Appeared in BioNews 614

European researchers have linked ovarian stimulation in women aged over 35 to increased chromosomal abnormalities.

Genetic screening shows that the production of oocytes is disrupted during fertility treatment involving ovarian stimulation. This process uses hormones to promote the release of a greater number of oocytes than normal and, in general, larger doses are given to women over 35, who need more help producing eggs.

This research shows it can lead to abnormal chromosomal copy numbers, a condition known as aneuploidy. This is detrimental to both conception and fetal development, and can result in the failure of IVF, miscarriage and disorders such Down’s syndrome (where there are three copies of chromosome 21).

Immediately prior to ovulation and subsequently following fertilisation, healthy oocytes go through two phases of a special kind of cell division called meiosis. Successful meiosis requires chromosomes to separate from each other at the correct time. During each phase small cells called polar bodies are produced, which when analysed can provide an insight into the chromosomal make-up of the eggs.

Researchers from nine countries, including the UK, screened the polar bodies of 34 women aged between 33 and 40, who were undergoing IVF with ovarian stimulation.

'Our evidence demonstrates that, following IVF, there are multiple chromosome errors in both meiotic divisions, suggesting more extensive premature separation of single chromosomes resulting in… multiple chromosome copy number changes in individual oocytes', said Professor Handyside, director of the London Bridge Fertility, Gynaecology and Genetics Centre, who led the research.

He told the Times that the errors seen in these women were 'opposite from what we see in pregnancies following natural conceptions. It raises the question of whether the stimulation is causing those errors'.

These findings may in the future prove helpful to couples undergoing IVF. 'This… is already a big step forward that will aid couples hoping for a healthy pregnancy and birth to be able to achieve one', said Professor Joep Geraedts, co-ordinator of the European Society of Human Reproduction and Embryology (ESHRE) Task Force on PGS (preimplantation genetic screening), who was involved in the study.

Professor Handyside added: 'We need to look further into the incidence and pattern of meiotic errors following different stimulation regimes including mild stimulation and natural cycle IVF, where one oocyte per cycle is removed, fertilised and transferred back to the woman. The results of such research should enable us to identify better clinical strategies to reduce the incidence of chromosome errors in older women undergoing IVF'.

These findings were announced on 4 July at the 27th annual meeting of ESHRE in Stockholm, Sweden.

The Independent | 04 July 2011
Could ovarian stimulation cause an increase in oocyte chromosome abnormalities?
EurekAlert | 04 July 2011
Guardian | 04 July 2011
BBC News | 04 July 2011


21 May 2012 - by Dr Greg Ball 
A senior IVF doctor has voiced concerns over health risks to women in IVF treatments that are commonly practiced by UK clinics...
16 April 2012 - by Cathy Holding 
A leading fertility expert in the USA has warned of young women's have serious misconceptions about their own fertility...
19 March 2012 - by Dr Lamiya Mohiyiddeen and Luciano Nardo 
IVF is a complex treatment for infertility requiring costly drugs and carrying significant risk of complications. Part of the procedure aims to stimulate the ovaries to produce more eggs, and conventional methods include a combination of hormones to induce follicle growth, from which eggs are collected...
22 August 2011 - by Heidi Colleran 
Two US studies published this week have shed light on how a gene mutation can change the number of chromosomes present in the cells of more than 90 percent of cancers...
15 August 2011 - by Dr Tamara Hirsch 
Rhythmic activity detected in newly fertilised mouse eggs may provide a novel and non-invasive screening method for identifying embryos most likely to survive a full-term pregnancy, according to research published in Nature Communications...

31 May 2011 - by Dr Rosie Gilchrist 
Multiple genetic tests have been performed on a single embryo for almost the first time, according to US researchers. The researchers from John Hopkins School of Medicine say their technique for making copies of an embryo's DNA can improve IVF success rates...
04 October 2010 - by Matthew Smart 
Researchers have found a molecule that they believe plays a key role in ovarian hyperstimulation syndrome (OHSS) - a potentially life-threatening condition that can arise from IVF treatment....
06 September 2010 - by Chris Chatterton 
Researchers from Newcastle University have announced that they have a better understanding of 'why older women are more likely to produce abnormal eggs, increasing the risk of infertility...
01 November 2009 - by Nienke Korsten 
According to figures published in the British Medical Journal last week, the number of diagnoses of Down syndrome in babies and fetuses in England and Wales has risen by 71 per cent over the past 20 years. This is attributed to an increase in maternal age over this period. A concurrent increase in terminations of affected pregnancies as a result of improved prenatal screening methods has meant that numbers of live births with Down syndrome have fallen by one per cent, whereas they would have ...
14 April 2008 - by Dr Rachael Panizzo 
By Rachael Dobson: A milder form of IVF treatment that has fewer side effects and is less expensive does not reduce the chances of a successful pregnancy, according to a new study. Research led by Dr Marinus Eijkemans, at Utrecht University Medical Centre in the Netherlands, reported that the milder...

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