One-embryo rule 'reduces chances of IVF success' as two give women better prospects of getting pregnant
Childless women have a better chance of success with IVF if they ignore official guidelines and use two embryos rather than one, researchers say.
The study challenges the view of IVF watchdog the Human Fertilisation and Embryology Authority, which says no more than one embryo should be implanted because of the risk of multiple births.
Such births, it says, are more likely to be premature and lead to disability.
One at a time Researchers say childless women have a better chance of success with IVF if they ignore official guidelines and go for two embryos instead of one
But the latest research, by British scientists, found that data from more than 33,000 IVF births showed two embryos maximised the chances of having an IVF baby.
Using three embryos however is no better than two, and the study found it was linked with an increased risk of birth complications.
Some fertility clinics have been accused of risking women’s health by implanting multiple embryos to increase the chances of a live birth.
Now all clinics must have a strategy for reducing multiple births, although there are no legal penalties.
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The policy is chiefly aimed at women aged 35 and under, who have the best chance of a baby using a single embryo because their eggs are usually in better condition than those of older women.
The HFEA says last year’s target to reduce the proportion of multiple IVF births to 20 per cent was met. The target for 2011/12 is 15 per cent.
However, study authors Professor Debbie Lawlor, of Bristol University, and Professor Scott Nelson, from Glasgow University, want patients to have ‘greater freedom’ to decide whether to use one or two embryos.
Evidence: According to the study of over 100,000 IVF cycles, the live birth rate was greater with the transfer of two embryos than with one
The study analysed 124,148 IVF cycles resulting in 33,514 live births, with rates of live birth, multiple births, and premature birth compared in women over and under 40.
In both age groups, live birth rate was greater with the transfer of two embryos than with one, while older women were less likely to encounter adverse outcomes.
Writing in The Lancet medical journal, they said: ‘We found that the number of embryos successfully fertilised affected the outcomes, so that in a younger woman with only two or a small number of embryos successfully fertilised there may be a case for transferring two, rather than just one.’
But the scientists added: ‘A clear implication of our study is that transfer of three embryos should no longer be supported in women of any age.’
The HFEA said: ‘Patients must weigh the chance of a live birth against the risks associated with a twin pregnancy and birth, both for herself and her baby.
‘We will study these findings further over the coming months to see whether our guidance should be revised.’