IVF checklist 'increases success'
Experts say they have found a way to avoid the higher risk of twins through IVF without reducing the success rate.
Internationally, clinics often transfer more than one embryo per IVF cycle to boost the odds of it working.
But this is riskier for mother and baby and some governments, including the UK, recommend single embryo transfer.
Now doctors say they can predict who will get pregnant with one embryo using a checklist of questions, and so only transfer more where essential.
At a meeting of the European Society for Human Reproduction and Embryology (ESHRE) in Stockholm, experts heard how running through a simple checklist of questions about the patient could bring down the risk of causing twins to virtually "normal".
In other words, women undergoing IVF would have a one-in-50 or two per cent chance of having a twin - the same as women conceiving naturally.
Currently, multiple births account for over 20% of IVF births in the UK.
UK fertility regulator the HFEA says clinics must bring this down to no more than 15% and, ultimately, it aims to cut this to 10%.
Dr Jan Holte of the Uppsala Science Park, who led the latest research, says the UK could learn from the experience of clinics in Sweden.
Over a four-year period between 1999 and 2002, Dr Holte and his colleagues analysed over 3,000 of the IVF cycles performed at their clinic, taking note of different factors that played a role in the treatment's success.
They found four factors - age of the woman, how many eggs she produced, quality of the resultant embryo and past success or failure with IVF - could predict the chances of pregnancy.
Using the information, they were able to strike a balance between making sure the treatment worked and reducing the twin rate by only transferring more than one embryo when absolutely essential.
In this way they were able to get their twin rate down from 26% to two per cent.
And, importantly, this meant better outcomes for the patients involved. Fewer babies were born prematurely and the baby death rate before, during or shortly after birth was more than halved.
Another clinic in Sweden has had similar success using the model, and now three more have started to use it.
Dr Holte said: "These improved outcomes were entirely due to the lower rate of twins."
Tony Rutherford of the British Fertility Society said: "This shows that you can get the twin rate back down towards almost normal, and so taking away the risk of multiple pregnancy from assisted reproduction treatment. That is an important step forward."
Richard Kennedy of the International Federation of Fertility Societies said: "Multiple pregnancy is a global and avoidable issue with IVF.
"Fertility specialists are continually looking for ways of transferring as few embryos as possible, while maintaining the success rates of the IVF cycle."