23 February 2009
ByAppeared in BioNews 496
A large study has investigated the potential genetic risks to children conceived by IVF. It confirms earlier research indicating that babies born following assisted conception have a small increased risk of certain genetic health problems.
The New York Times reports that in November last year, the Centers for Disease Control and Prevention (CDC) in Atlanta, reported that IVF babies have a slightly increased risk of several birth defects, including a cleft palate, and a hole between the chambers of the heart. The study included 9,584 babies with birth defects, of which 2.4 per cent were conceived using IVF, and 4,792 babies without birth defects, of which 1.1 per cent were conceived by IVF.
Although the findings of the study are considered preliminary - any baby has a three per cent chance of developing a birth defect - Richard M. Schultz, associate dean for the natural sciences at the University of Pennsylvania believes 'there is growing consensus in the clinical community that there are risks [in IVF]'. This view is shared by Dr Alistair Sutcliffe of University College London, an expert in the field who is 'less optimistic about the things that are known about the health of the children' born after IVF and related procedures.
Concerns were first raised over the possible risks of IVF several years ago, when studies indicated an increased risk of certain rare 'imprinting disorders', which are inherited conditions caused by changes in gene activity. Dr Andrew Feinberg, a professor of medicine and genetics at John Hopkins University, Baltimore, US became concerned about the lack of information about IVF and its effect on gene expression whilst studying gene activity which can lead to cancer. During a study of children with the imprinting disorder Beckwith-Wiedemann syndrome (BWS), characterised by a susceptibility to childhood cancers, parents who had had IVF treatment began to ask whether it may have caused the syndrome.
On investigation of the prevalence of IVF in the pregnancies which resulted in children with BWS, Feinberg concluded that about ten times more patients had used IVF procedures than would normally be expected. However, it is not clear whether these BWS cases were related to the infertility of their parents, or caused by something in the IVF process itself.
Since the beginning of the IVF revolution, scientists have been aware that the culture medium or 'broth' that embryos were grown in might have an effect on how quickly they developed. Certain qualities of media used in IVF procedures can affect the presence or absence of activity of certain groups of genes, and whether or not they become 'switched on' during development.
Dr Schultz has said that if the development of mouse embryos in any way reflects what can happen in humans, there is no question gene expression can be altered by the process of growing embryos in a laboratory. Yet Dr Elizabeth Ginsburg, president of the Society for Assisted Reproductive Technology pointed out that working out what, if anything, in a culture medium might affect the development of a human embryo would be a difficult process, as IVF centres use multiple media during the procedure. In addition to which, the effects of changes in gene activity - so-called epigenetic changes - may not become apparent until adulthood or old age.