An Australian study of 37 babies born with Beckwith-Wiedemann Syndrome (BWS) adds to the evidence linking in IVF and the condition.
The researchers, from Murdoch Childrens Research Institute in Melbourne, looked at 37 babies born with BWS. They found a birth prevalence of one in 4000 in children born from IVF, compared with between one in 15,000 and one in 35,000 for those naturally conceived.
American researchers at Johns Hopkins University and the University of Washington first made the link between IVF and BWS. Published in January 2003, their research involved 65 BWS children and found a prevalence in IVF children of one in 2500. UK researchers later confirmed this finding in a study of 149 children.
BWS is a genetic condition resulting from a fault in a process called imprinting, where only one copy of a particular gene is switched on. In people without BWS, only the paternal copy of a gene called IGF2 is switched on, but in people with the condition, both copies are active. IGF2 codes for a growth factor; the symptoms of the disease include large tongue and a higher predisposition to tumours.
Jane Halliday, who led the research, said that the findings did not prove IVF was dangerous or that it should be avoided. Rather, she said, it 'adds to the information that should be available to couples considering assisted reproductive technologies'. She continued: 'There have been more than a million IVF babies [born] around the world. If there was something obvious that IVF was doing we would know about it. We will continue to monitor pregnancies'.
Research carried out in Portugal earlier this year, points to another possible cause of higher BWS frequency in IVF births. Of 127 men studied, 24 per cent of men with low sperm counts were found to have imprinting abnormalities, whilst men with normal sperm counts had no such genetic defects.