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Latest Surrogacy News
Older dads
not in the swim
The Courier Mail 26 April 2004
FOR decades career women have been deafened by the
ruthless ticking of the biological clock.
The parental perils for women who ignore its warnings
are well known. However, it's now been found that men
also need to be clockwatchers.
For the first time,
researchers in the US have made a link between age and
male fertility and the hazards of older fatherhood.
According to
researchers at the University of California, sperm get
sluggish as men age and lose their ability to "swim" to
an egg. Also, fewer sperm are produced.
Other research in the
UK and the US has found that sperm quality also can
decrease. As men get older, the DNA – the genetic
blueprint for a new life – may start to unravel. As a
result, these damaged sperm are less able to fertilise
an egg. Even if penetration does occur, the embryo may
fail to implant in the womb or the woman may miscarry.
This will be bad news
for blokes who blithely believe they can reproduce
easily and successfully into their 50s or 60s.
After all, glossy
magazines gush about the likes of Sir Paul McCartney's
becoming a new dad at 61 or Julio Iglesias Sr's baby
surprise at 87, giving men badly informed faith in their
virility.
However, less quality
sperm is not the only hazard for older men who thought
the sole challenge would be having the energy to play
footy with junior.
Several genetic
conditions also have been linked to mature-aged dads,
such as schizophrenia and achondroplasia dwarfism. More
worrying is that new research also has found that
paternal parental age can effect the lifespan of
daughters.
This groundbreaking
research from the University of Chicago's Centre on
Ageing was presented at a longevity conference in Sydney
recently. Dr Natalia Gavrilova says late parenthood is a
particularly bad idea for men who father daughters.
"When people are
postponing having children until later in life because
of their careers they should be aware of the down side,"
she says. "Men should know that there might be some
problems for them, too."
Gavrilova's research
found that daughters born to fathers in their late 40s
or older live, on average, three years less than other
women. She blames this sex-specific lifespan shortening
on the X chromosome, which is only inherited by females.
This inherited chromosome could be damaged by the effect
of cell division on the quality of parental germ cells.
The mutation rate is
much higher in males than in females meaning we can
expect a much higher accumulation of DNA damage in
paternal germ cells.
Also, the age of the
father is the main factor determining the human
spontaneous mutation rate. For women the estimated
number of cell divisions between zygote and egg is 24
and this is independent of age. In men, however, the
number of cell divisions between zygote and sperm is
much larger. At age 13 the number of divisions needed to
make sperm is 13 but, by the time a man turned 50, the
number of cell divisions has increased to 800.
"Every cell division
makes a copy of DNA," Gavrilova says. "And the same
thing happens with the next division and this final copy
is of less quality. This can introduce a slight risk of
error in the genetic material of the new sperm. You can
call it a kind of copy error.
"We have found then
that there is an optimum age for fatherhood. Too young
fathers is not good either. The optimal age for men to
conceive children is 30 to 35."
Maybe, however, trends
in most Western countries show that men, like women, are
leaving parenthood until later in life. In the US there
has been a 25 per cent increase in the birth rate for
fathers aged 35 to 54 since 1980. In Australia, ABS
figures show the median age of fathers was 30.2 in 1986,
rising to 32.3 in 2001.
According to the
Fertility Society of Australia, one in six couples has
trouble conceiving.
Not all fertility
problems are age-related, however. Infertility in men
relates to their inability to produce healthy sperm.
The new research in the
US suggests age could be a factor and this knowledge
should refocus the late parenthood debate on the role of
the father as well as the mother.
The study by the Centre
for Children's Environmental Health Research showed when
the subject's age increased from 22 to 80 there was a
continuous reduction in sperm motility as well as semen
volume. Among the 97 men studied, there was a
20 per cent decrease in semen volume in 50-year-olds
compared with 30-year-olds.
The research results
are no surprise to fertility expert Dr Anne Clark. She
says 50 per cent of couples who come to fertility
clinics looking for help do so because of male
infertility.
"The man's part in this
has been ignored," says Clark, medical director of
Fertility First Centre for Reproductive Health in
Sydney. "Women having babies in their late 30s tend to
be married to men who are that age as well but all of
the responsibility has been put on the woman. That is
not correct. If she had a younger man she might be
better off.
"Often it is not that
women have wanted to wait until later in life to have a
baby. It takes two to tango. We find in our practice
that a woman is past her ideal fertile time but it is
not her choice – it is just that her partner has taken
that long to feel comfortable with being a father. It is
a big issue as women who want babies younger either have
to elect to be a solo parent with a sperm donor or hang
out to be an older parent."
Falling sperm counts
remain a worldwide concern. A recent British study of
7500 men showed the average sperm count fell in the past
decade from 87 million sperm per millilitre of semen to
62 million. One could be forgiven for thinking this is
just a mere drop in the vast fertility ocean. However,
50 years ago the normal sperm count was about
113 million – double what it is today. Pollution,
pesticides and chemicals are believed to be to blame.
So what is a potential
older dad to do to save his sperm? If going bush isn't
an option, Clark suggests they should have an early
sperm check, followed by "clean living and no
recreational drugs". Sex, however, is OK.
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