Couples contemplating fertility treatment should be warned about the risks of birth defects, which are up to twice as common as when conception is natural, researchers say.
The largest study of the incidence of congential abnormalities in babies born following fertility treatment found that 4.24 per cent were affected by major malformations compared with the expected rate of 2 to 3 per cent.
Although the rate is still low, the number of babies born following fertility treatment is growing each year. In all about 200,000 such babies have been born in Britain since 1991, implying that as many as 8,000 may be affected. Fertility treatment includes IVF and other invasive treatments as well as treatment with drugs alone to stimulate ovulation.
The survey of 15,000 births in 33 centres in France was conducted from 2003 to 2007. The results showed increased malformations of the heart and genitals, more common in boys, and of angiomas, minor benign tumours made up of small blood vessels on or near the surface of the skin, which were more common in girls.
Geraldine Viot, from the Maternite Port Royal Hospital in Paris, presented the results at the annual meeting of the European Society of Human Genetics in Gothenburg, Sweden. She said previous studies had indicated a malformation rate of up to 11 per cent.
"Given that our study is the largest to date, we think that our data are more likely to be statistically representative of the true picture," she said. "At a time when infertility is increasing and more couples need to use ART [assisted reproductive technology] to conceive, it is vitally important that we find out as much as we can about what is causing malformations in these children, not only so that we can try to counteract the problem, but also in order for health services to be able to plan for their future needs."
Responding to the finding, the Human Fertilisation and Embryology Authority said: "The reason for [the increase in abnormalities] is not clear and the risks are still very small. It is important that patients are informed about this but not alarmed by it."
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