Almost half the 5,601 babies born in the UK as a result of IVF in 1996- 97 were from multiple pregnancies, which carry a higher risk of complications and impose heavy emotional and financial pressures on parents.
The incidence of twins has almost doubled and that of triplets has trebled since the early Eighties after remaining level for the previous 50 years, largely as a result of infertility treatment.
New guidelines to be issued by the college in the New Year will say that the three embryos replaced in each cycle of IVF treatment - the maximum allowed by the Human Fertilisation and Embryology Authority which licenses the clinics - should be reduced from three to two.
The measure is likely to be opposed by some fertility experts who claim it will reduce the chances of success for older women and for those who have had repeated failed attempts.
The debate will be fuelled today by research published in The Lancet which shows that the risk of a multiple birth after IVF is 25 times higher than after natural conception. Researchers from Sweden who compared 5,850 IVF births between 1982 and 1995 with 1.5m in the general population also found that the IVF babies were more likely to be born prematurely, with low birthweights and with a higher rate of certain malformations.
The investigators say: "The clinical practice of IVF needs to be changed to lower the rate of multiple pregnancy."
Their conclusion is backed by two British experts, Professor Nicholas Fisk of the department of fetal medicine at Queen Charlotte's Hospital, London, and Geoffrey Trew, consultant obstetrician at Hammersmith Hospital. In a commentary in the journal, they say that the growth of multiple births is now an "epidemic" and that the only way to avoid triplets is to avoid three embryo transfers.
Professor Fisk said yesterday: "Twins are a problem but triplets are a disaster. Women pregnant with triplets are shocked when I go through the obstetric risks with them. Triplets have nine times the death rate per baby and 47 times the risk of cerebral palsy compared with a singleton pregnancy. Twins have eight times the risk of cerebral palsy. This is an epidemic we have got to stop."
Many clinics now only transfer two embryos per cycle, since the findings of a study in The New England Journal of Medicine last year, which suggested that transferring two embryos was just as effective as transferring three. One of the study's main authors, Professor Allan Templeton, of Aberdeen University, is secretary of the Royal College of Obstetricians and has been closely involved in drawing up the new guidelines.
The Human Fertilisation and Embryology Authority is to debate the issue at its annual conference in December but Suzanne McCarthy, chief executive, said while the group was very concerned about multiple births and strongly favoured clinics discussing with patients the optimum number of embryos to have transferred, there were no plans to change the policy.
Professor Fisk said the "ultimate goal" was single embryo transfer.Reuse content