 News
16th March 2008
Male fertility
is set in the wombMale fertility problems are determined in the
womb, research from the University of Edinburgh suggests. Common genital
disorders, low sperm count and testicular cancer could all be linked to hormone
levels early in pregnancy, studies in rats suggest. It was found that levels
of male hormones, such as testosterone, in a critical "window" at 8-12 weeks determine
future reproductive health. The results are published online in the Journal
of Clinical Investigation. Problems with reproductive development such
as the testes not descending properly into the scrotum (cryptorchidism) or the
urinary tract opening in the wrong place on the penis (hypospadias) are fairly
common in young boys. Other disorders, such as low sperm counts and testicular
cancer, are thought to be part of the same pathway. Using the mouse model,
researchers at the Medical Research Council Human Reproductive Sciences Unit found
the disorders resulted from low levels of male hormones - or androgens - at the
equivalent to 8-12 weeks human gestation. They also found that the level
of androgen hormone at this time was related to the distance between the base
of the penis and the anus. This measurement could be an early warning system
of future reproductive problems in baby boys, they said. It could also give insights
into links between hormones in the womb and fertility problems in later life.
Study leader, Dr Michelle Welsh, said: "We know from other studies that
androgens work during foetal development to programme the reproductive tract.
"But our assumption was that it would be much later in pregnancy." She
added the anogenital measurement would be a useful tool. "Say a clinician
were to examine a 30-year-old man with testicular cancer - previously there would
have been no way of knowing what hormones he was exposed to in the womb. "We
would suggest that this measurement, even at this later stage in life, could offer
an indication of hormone exposure. "For example, the shorter the distance,
the less confident we can be that hormones have acted correctly and at the right
time." Co-author, Professor Richard Sharpe, said around 7 per cent of boys
had cryptorchidism and low sperm counts effect as many as one in five young men.
Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield,
said scientists had been worried for many years about the increasing incidence
of problems resulting from disrupted development of the male reproductive system
during pregnancy. "Understandably, this is almost impossible to study in
humans directly and so animal models are needed to unravel the precise details.
"To use the adult anogenital distance as a proxy marker of foetal exposure
in utero is a good suggestion and I would encourage studies to investigate how
well this correlates with problems of the male reproductive system." Where
to next? | 
