IVF Treatment - Single Embryo Transfers (SET)

The number of assisted reproductive technology (ART) cycles continues to rise each year. According to the European Society of Human Reproduction and Embryology (ESHRE) about 1.5 million ART cycles are now performed globally each year. In the past, when technologies, like ICSI, were new and pioneering, the culture within IVF clinics was to transfer more rather than less embryos. Historical data wasn’t as readily available as it is today on the efficacy of IVF treatments. The aim was to be responsible but also to maintain a good success rate. However, as treatments improved so did an increase in the multiple birth rate. It is believed that 1 in 4 of all IVF pregnancies will result in a multiple birth.

Why are multiple births so frowned upon? Some women undergoing IVF treatment would gladly have twins. Medically it is clear that there are serious risks to the mother and babies. Mothers with multiple pregnancies are more likely to suffer from pre-eclampsia and gestational diabetes. Whilst twins and triplets are more likely to be born early compared to singletons and are therefore premature and of low birth weight. This means that they are more likely to suffer from health problems both short-term and long-term.

In 2008 the Human Fertilisation and Embryology Authority in the UK agreed a 4-year policy to reduce the incidence of multiple births following ART. As a result, the multiple birth rate has been reduced and, in October 2012, a target rate of 10% came into effect. This means that no more than 10% of the births at each clinic should be twins or higher-order births. In Europe, some countries have already adopted SET policies and are ahead in reducing the incidence of multiple births. According to the ESHRE annual report on IVF for 2008 published this year, the multiple delivery rate has declined marginally in Europe.

Providing information to patients on the benefits of SET is important. Improvements in IVF techniques for freezing embryos should mean that patients should have more confidence in freezing their surplus embryos. In addition, extended culture to blastocyst is now routine. This means that the embryologist can confidently select one good embryo which has achieved all the developmental milestones thereby maximising the chances of implantation. Further selections based on monitoring the cleavage rate of the developing embryo or through genetic screening will add further selection criteria. Furthermore, research has shown that while single blastocyst transfer reduces the incidence of twin pregnancies compared to double blastocyst transfer, it has no adverse effect on implantation rate per se.

Whilst European clinics are trying to reduce the incidence of multiple births, there are undoubtedly reasons why some people will still want to have a double embryo transfer. People who travel abroad for IVF will have invested a huge amount of time, energy and money in an effort to fulfil their dreams. It is very difficult for a clinic treating a foreign patient to insist on SET. However, outlining the clear advantages will ensure that any on-going pregnancy back home has the best chance of a healthy outcome.

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