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King's College London - Health: More than a medical matter

Single blastocyst transfer successful in women over 35

08 October 2007

By Katy Sinclair

Appeared in BioNews 428

Californian researchers have reported that women over 35 can avoid multiple births by using an IVF method that transfers only a single embryo. A team led by Dr Amin Milki from Stanford University, reporting in the journal Fertility and Sterility, announced that half of the women they had studied became pregnant after undergoing the single blastocyst transfer method.

The current recommendations from the American Society for Reproductive Medicine (ASRM) advise that doctors should transfer two or more embryos into women over 35, to enhance the chances of a successful pregnancy. However, transferring more than one embryo can lead to multiple births, which carry a higher risk for both mother and fetus.

The single blastocyst transfer method involves bathing an embryo in a culture of nutrients for five days, until it reaches the blastocyst stage of development. The doctors then determine which embryos are most likely to lead to a successful pregnancy, and transfer them into the woman's uterus.

The study reviewed data from 45 patients between the ages of 35 and 43, who had decided to use the single blastocyst transfer method, at the Stanford University Medical Centre. The procedure is offered to those with good quality embryos who elect to have only one embryo transferred. In the US almost 60 per cent of IVF procedures are carried out on women over 35. The team found that 28 pregnancies were conceived, with 23 continuing beyond the first trimester. Dr Milkie said that this was 'an excellent pregnancy rate'.

Although the quality of the women's embryos meant that they had a relatively good chance of conceiving, the national success rate for IVF procedures in women aged between 35 and 43 is only 25 per cent. Dr Milkie stated that 'although these results represent a selected group of patients, we believe that they should serve as encouragement to patients and providers who are considering single blastocyst transfer in the older IVF population'.

Dr Milkie noted that the preference for one child in the group studied was not always due to health reasons, but because half of the patients already had one child and wanted just one more. However, many women are willing to risk the outcome of multiple pregnancies, because the IVF success rate is higher when multiple embryos are transferred. Dr Milkie said that the study gave reassurance that a good pregnancy rate is possible without risking multiple births. However, he conceded that for women whose embryos were of a lower quality, transferring two or three embryos might give them a better chance of pregnancy.


New IVF technique may enable pregnancy without multiple births | 02 October 2007
Pregnancy without multiple births enabled by new IVF technique
Medical News Today | 02 October 2007
MedPage Today | 02 October 2007
Science Daily | 02 October 2007


31 January 2011 - by Tamara Hirsch 
A recent review paper has emphasised the need for improved provision of fertility information, especially regarding age-associated risks, as the trend for women having children later in life continues.... [Read More]
08 September 2008 - by Antony Blackburn-Starza 
The British Fertility Society (BFS) and the Association of Clinical Embryologists (ACE) have introduced new guidelines aimed at reducing the number of multiple births amongst IVF patients in the UK. The guidelines, published in the journal Human Fertility, recommend that a single embryo transfer (SET) policy should... [Read More]
26 February 2008 - by Dr Rebecca Robey 
Scientists at a UK fertility clinic have reported that a new IVF technique may increase the rate of pregnancy whilst decreasing the risk of multiple births. The study, published in the British Journal of Obstetrics and Gynaecology, involved nearly 2500 women over a three-year period and found... [Read More]
10 December 2007 - by Dr Kirsty Horsey 
The UK's Human Fertilisation and Embryology Authority (HFEA) called last week for a new national strategy designed to reduce the number of multiple births from fertility treatments, as a result of which it expects to see the multiple birth rate to fall to 10 per cent... [Read More]

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