PREGNANT women have been advised to avoid using perfumes or scented body creams after research suggested the products can cause unborn boys to suffer infertility or cancer in later life.
Research on rats carried out by Professor Richard Sharpe has found that the reproductive system of male foetuses can be damaged as early as at eight weeks' gestation by chemicals including those found in many cosmetics.
The damage can result in infertility or testicular cancer – both growing medical problems across the world – said Sharpe, principal investigator at the Medical Research Council's Human Sciences Unit.
Sharpe, who will unveil his findings at a major conference on fertility in Edinburgh this week, has discovered a "time window" at 8 to 12 weeks' gestation – before some women even know they are pregnant – during which certain hormones in the foetus are activated and the male reproductive system is established.
Sharpe has found that future problems with male fertility including undescended testicles, low sperm count and the risk of testicular cancer could be determined at this time if these hormones, such as testosterone, do not work properly.
Experiments on rats have confirmed that if the hormones are blocked the animals suffered fertility problems.
Sharpe told Scotland on Sunday: "We have found the male programming window, which occurs far earlier in foetal development than was previously thought, before the reproductive organs fully develop. This is when the androgens such as testosterone in the foetus are at their most active.
"If the male foetus does not receive enough androgens it may not realise its full reproductive potential, including the size of the penis and testes, undescended testes or the sperm count. The chances are, something will be wrong with the reproductive system. It may be one thing or several things.
"Women could stop using body creams and perfumes. Although we do not have conclusive evidence that they do harm, there are components about which there are question marks; for example it could be certain combinations of chemicals. If you are thinking about how a baby might be exposed, that's one way, and it's something positive you can do. It might have no consequence, but it's something positive women can do for their baby."
Sharpe will reveal his findings this week at the Simpson Symposium in Edinburgh, a gathering of fertility experts organised by Edinburgh University.
Up to 8% of boys are thought to be born with undescended testicles, which is the most common birth defect in boys and is linked to infertility. The condition is also a risk factor for developing testicular cancer later in life.
Sperm quality and number have declined in the last 30 years. About one in seven couples in the UK will have difficulty conceiving at some time. About one third of cases are due to problems in the man.
Testicular cancer is also increasing worldwide by between 1% and 6% a year. The annual number of new cases of testicular cancer in the UK grew from 850 in 1975 to 1,889 in 2004.
However, campaigners urged women not to panic over the suggestion until further studies are conducted.
Susan Seenan, spokeswoman for the charity Infertility Network UK,
said: "A lot of women will not even know they are pregnant at this stage, or how far along they are. I would be very concerned about alarming women until these tests have been done on humans. We welcome any new research in infertility but we would like to see a lot more research in this area before the findings on animals can be said for humans."