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Scientists evolve
method to postpone motherhood
Report
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A
method of storing human eggs which allows women to postpone
motherhood is as safe as conventional IVF treatment, research
suggests.
A Canadian study, published in the journal Reproductive Biomedicine
Online, looked at 200 children conceived using “vitrified” eggs.
The technique involves rapid freezing, and could also help women
whose fertility is threatened by cancer.
A UK expert said it was encouraging - but more research was needed.
Although sperm and embryos are often frozen and successfully thawed,
early ways of freezing eggs have proved far less successful.
The formation of ice crystals in the liquid within the egg can
damage its structure, rendering it unusable.
“Vitrification” involves the removal of water from the egg, the
addition of an “antifreeze” solution, then “flash freezing” in
liquid nitrogen.
It is suggested that up to 95% of eggs survive the process, compared
with 50% to 60% using older methods.
It is already available at a handful of clinics in the UK, costing
up to £3,000, plus a small fee for annual storage.
Women have a fixed number of eggs to last them a lifetime, and
fertility drops sharply from the late-30s onwards as the number of
eggs dwindles.
Effective and safe egg-freezing methods would allow eggs to be
harvested, then used to produce an IVF pregnancy later in life.
Aside from the wish to delay motherhood beyond their 30s and 40s,
some women may use this technique for medical reasons, perhaps if
they are facing cancer treatment which will render them infertile,
or a premature menopause.
The researchers, from McGill university in Montreal found that the
rate of birth defects among the 200 children conceived using
vitrified eggs as 2.5%, roughly the same as in natural pregnancies
and IVF.
Dr Allan Pacey, the secretary of the British Fertility Society (BFS),
said that more, similar, studies would be needed before the safety
of the procedure could be established.
“The British Fertility Society would say that this should only be
offered in the UK as part of a controlled trial.
“We are getting close to the stage where I would be comfortable
offering this to women who are about to have chemotherapy for
cancer.”
He said that, although the BFS had no policy on using egg-freezing
for “social” reasons, his personal view was that there were no
ethical problems with offering women the chance to plan their
families in this way.
“We have been offering men the chance to freeze their sperm for this
reason for years now, and I don’t really see any great difference
between the two. Why shouldn’t women have the same opportunities as
men?”
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