A British fertility expert claims that the lack of laboratory research into IVF means scientists are effectively "experimenting on children".
Lord Winston is a well-known IVF researcher
Lord Robert Winston said that more animal studies should be attempted to make sure techniques were safe before they were tried on humans.
Speaking at the British Association Festival of Science, he said there was a bias against lab research.
A government-funded study into the safety of IVF is currently underway.
Lord Winston told the BBC that he did not intend to alarm parents of IVF children.
However, he said he felt that some techniques, such as the freezing of embryos, and the practice of growing embryos in the test tube for an extra couple of days prior to transfer, had not been sufficiently tested in animals - or on "spare" human embryos - prior to their use in humans.
He said: "One has to experiment on humans to improve medicine - I don't think there's anything wrong with this provided there's proper information about what is being done.
"Many of these things have not been tested properly using animal models, or more importantly, using spare embryos.
"There is an environment both here and in the US where there is quite a lot of antipathy towards decent laboratory research."
Lord Winston blamed the commercial focus of many IVF clinics for the lack of funding for IVF research outside humans.
He said that a lot of techniques currently employed in mice had not been fully tested, even in mice.
Thousands of women rely on frozen embryos
Research at Lord Winston's own lab at the Hammersmith Hospital in London suggested that embryo freezing might cause subtle genetic mutations, although the impact of these was less clear.
He said: "If you are using treatments that might damage somebody - such as an unborn child - then you have a duty to tell people."
The Medical Research Council embarked on a massive study on IVF safety last year. It has yet to report its findings.
Suzi Leather, who chairs the Human Fertilisation and Embryology Authority - which regulates the industry - said that IVF was "essentially a safe technique".
She added: "It is important that we continue to monitor and assess all
research and development in assisted reproductive technologies.
"The working group is currently undergoing a detailed review of relevant studies in order to make recommendations for further research.
"The working group is hoping to complete its review and decide on areas for additional research by the end of 2003."
The UK is preparing for a massive expansion in IVF funding by the state.
The government's independent medicines advisory group, the National Institute for Clinical Excellence, is proposing that many more infertile couples should have access to IVF on the NHS.
A final decision on this should be made early next year.