(May7, 2012)

One in 10 children conceived by fertility treatment ICSI have birth defects, the largest study of its kind shows. ICSI is used in about half of UK fertility treatments.

The risk of a birth defect after natural conception is 5.8 per cent compared with 7.2 per cent following IVF and 9.9 per cent after intracytoplasmic sperm injections, known as ICSI, according to research published in the New England Journal of Medicine.

ICSI is primarily used for male fertility problems, however, and its risk significantly decreased when frozen eggs were used, according to the study's lead author, Associate Professor Michael Davies of the University of Adelaide.

Researchers at the university's Robson Institute examined 309,000 births in South Australia. Of these, 1,878 involved ICSI, in which sperm is injected into the egg, generally used when men have low sperm counts. In IVF, the sperm and eggs are mixed in a dish and sperm breaks into the egg on its own.

Researchers looking at a smaller subset in the study also found risk tripled among women who used the drug clomiphene citrate to stimulate ovary production. The drug is available online and is known to cause foetal abnormalities if the woman is already pregnant.

"While confined to a small group in our study, this is of particular concern as clomiphene citrate is now very widely available at low cost, and may easily be used contrary to manufacturers' very specific instructions, to avoid use if pregnant, as it may cause feotal malformations," Mr Davies said.

Since its introduction in 1992, increasing numbers of fertility clinics have adopted ICSI as their procedure of choice.

"The study suggests that while babies born from IVF are as healthy as their naturally conceived counterparts, there is still some residual risk to babies born through ICSI that currently cannot be explained," Dr Allan Pacey, chairman of the British Fertility Society, told The Telegraph.

Researchers did not determine whether the risks of abnormalities were a result of the ICSI technique or because men with lower sperm counts were more likely to pass on anomalies.

"It may well be that the families who have to use ICSI have extreme sperm damage, and this may be why there is a higher rate of anomalies in this group," said Professor Peter Illingworth, an associate professor at the University of Sydney.

Previous research suggested children conceived naturally among couples diagnosed with infertility had a risk of higher abnormalities, which indicates defects were more likely to be tied to infertility than to the treatment used to overcome it.

In 2005, the last year for which data was available, 5,935 babies were born as a result of IVF treatment compared to 5,265 babies born with the help of ICSI.

(Source: http://www.channel4.com/news/ten-per-cent-of-babies-conceived-with-icsi-have-defects )