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Last Updated: Wednesday, 16 February, 2005, 19:01 GMT
Chemical 'could aid IVF embryos'
IVF sample
IVF embryos are not developed using growth factors
Adding a key chemical to the fluid in which IVF embryos are grown could help prevent developmental problems in babies, scientists suggest.

Embryos which develop naturally are exposed to a range of chemicals in the female reproductive system.

IVF embryos are not, because of fears the chemicals could behave differently outside the body.

But in New Scientist, University of Adelaide scientists said mouse tests showed embryos did benefit.

Adding growth factors to embryo medium could also have unintended effects on people conceived by IVF
Dr Daniel Brison, St Mary's Hospital, Manchester
IVF has been linked to low birth-weight, which itself has been associated with an increased susceptibility to chronic disease in later life.

However, scientists are not certain if the link between IVF and low birth-weight is linked to how the embryos develop or to the parents' fertility problems.

In natural pregnancies, the developing embryo is exposed to chemicals including growth factors, which stimulate new cell development, before it implants in the womb.

IVF embryos are grown in a Petri dish for between two and five days, and are not exposed to growth factors.


The Australian researchers looked at the effect of exposing mouse embryos to one growth factor, GM-CSF, which has been identified as affecting cell development, in both mice and humans.

The team are involved in the development of a new 'medium' which could be used to grow embryos in.

Laboratory tests they carried out showed that mouse embryos developed without GM-CSF had restricted foetal growth, accelerated growth after birth, and that the mice tended to be fatter as adults, compared to embryos which developed naturally in the womb.

The team found that adding the GM-CSF growth factor to the fluid alleviated the effects on foetal and post-natal growth. However, it did not prevent obesity in adults.

Writing in the journal Endocrinology, where the research was also published, the team led by Dr Sarah Robertson, said: "This demonstrates that embryonic exposure to GM-CSF is essential for normal placental development and foetal growth."

Better understanding

Professor Alan Handyside, a fertility expert at the University of Leeds, said: "Embryos in vivo are exposed to a variety of growth factors.

"But the conditions in which IVF embryos are cultured are just different.

"For example, you can't maintain the same kind of oxygen concentrations, because air has a much higher concentration than blood."

Dr Daniel Brison, of the Department of Reproductive Medicine at St Mary's Hospital, Manchester, told the BBC News Website: "There us an argument that current media lack an important ingredient present in the maternal tract, which might be a growth factor, therefore arguably we should try adding them.

But he said: "The counter argument is that IVF works reasonably well in the absence of growth factors, and that there are potential risks to adding them because we do not understand the effects they might have.

"Adding growth factors to embryo medium could also have unintended effects on people conceived by IVF."

He said it was clear further research was needed.

A spokesman for the Human Fertilisation and Embryology Authority, said: "Although there is no formal regulation of culture media in the UK, our Scientific and Clinical Advances working group keep a close watch on issues which could affect the safety of IVF treatment and, we will continue to monitor the situation."


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