Most women having IVF will be allowed to use only one embryo at a time to guard against hazardous twin and triplet births, under new rules recommended to the Government’s fertility watchdog today.
The number of embryos that can be implanted in the womb should be cut from two to one for patients who have yet to reach their late 30s, an expert panel commissioned by the Human Fertilisation and Embryology Authority (HFEA) advised.
The stricter guidelines could be combined with a cap on the proportion of twin births at individual IVF clinics. Centres that routinely exceed a twin birth rate of 5 to 10 per cent would face further restrictions on embryo transfer, or even the loss of their licences.
At present, around 90 per cent of IVF procedures performed in the UK use either two or three embryos to improve the chances of conception. This is recognised as the biggest health hazard of infertility treatment, as it significantly raises the chances of conceiving twins or triplets: one in four IVF pregnancies ends in a multiple birth.
Twins are five times more likely than singletons to die in the first week of life, and the risk for triplets is nine times greater. Such children are also significantly more likely to be born prematurely or underweight, or with disabilities such as cerebral palsy.
Multiple pregnancies are dangerous for mothers as well: 25 per cent are complicated by problems such as high blood pressure, and death rates are doubled for women expecting twins. These health issues mean each twin costs the NHS 16 times as much as a singleton birth in the first year of life.
The HFEA first attempted to tackle the problem in 2004, by setting a limit of two embryos for women aged under 40, and three for older patients. The authority’s Expert Group on Multiple Births after IVF, however, has now ruled that these restrictions do not go far enough.
"We have got to do more to reduce the twin rate, as multiple birth is the single biggest risk to the health and welfare of a child born by IVF," said Professor Peter Braude of King’s College London, who chaired the panel. "Women should ideally be having healthy babies, one at a time."
Single embryo transfer would not be appropriate for every patient, but it should be tried first for those with a good chance of conceiving, Professor Braude said. This would usually mean women in their mid-30s or below, who produce at least one good quality embryo and who have not had failed attempts at IVF.
If a single embryo was made compulsory for all women aged 34 and under, it would have included 47.5 per cent of the IVF cycles performed in 2003-4. A threshold of 35 would take in 56.5 per cent of patients, and one of 36 would cover 64.6 per cent.
Many doctors and patients have resisted a move to single transfers for fear it would reduce the chances of conceiving, but Professor Braude said this need not be the case. Evidence from European countries that have adopted it for women with a good prognosis - such as Sweden, Finland and Belgium - shows that success rates can be just as good as when two embryos are used.
The best method is to transfer one embryo and freeze others for later use should the first treatment cycle fail. This "one plus one" technique has identical success rates to implanting two embryos at the same time, but almost eliminates the risk of twins. Frozen embryos can be transferred during a woman’s natural menstrual cycle without the need for drugs or invasive procedures, at a cost of around £600 compared to the usual £2,500.
In Sweden, more than 70 per cent of IVF cycles now use a single embryo, and multiple birth rates have plunged to 5 per cent. Overall success rates, however, have remained broadly unchanged, at just over 30 per cent. The average success rate in Britain is 21.6 per cent per cycle, but this climbs to 28.2 per cent in patients aged under 35.
The HFEA has yet to respond to the proposals, but it is widely expected to act on the panel’s advice. Last week, its interim chair, Lord Harries of Pentregarth, told The Times that he favoured moves towards single embryo transfer.
The report was broadly welcomed by medical and patient groups. Peter Bowen-Simpkins of the Royal College of Obstetricians and Gynaecologists said: "A decision to recommend single embryo transfer to women under the age of 35 is a pragmatic step forwards, in an attempt to reduce the incidence of multiple pregnancy, with its associated morbidity to both the babies and the mother."
Clare Brown, of Infertility Network UK, said the move must be matched by full implementation of the National Institute for Health and Clinical Evidence (Nice) recommendation that three cycles of IVF be provided free on the NHS.
"We share medical concerns regarding the risks of multiple births, both to the mother and children born," she said. "Without full implementation of the Nice guideline patients will not support any move towards single embryo transfer."
Some fertility specialists were also sceptical. Mohammed Taranissi, of the Assisted Reproduction and Gynaecology Centre in London, said more time was needed to assess the impact of cutting the limit to two embryos for women under 40, which is less than two years old.
"I am not against single embryo transfer but any restrictive policy on this would be counter to the principles of good medicine – that the clinician makes decisions about treatment based on the individual," he said. "If the HFEA moved towards adopting single embryo transfer indiscriminately it would probably result in a small decrease in twins but a larger number of people who do not become pregnant."
