X-Message-Number: 30002
From: David Stodolsky <>
Subject: Healthy women warned over egg freezing
Date: Thu, 8 Nov 2007 19:29:32 +0100

Healthy women warned over egg freezing

      * 14:55 17 October 2007
      * NewScientist.com news service
      * Roxanne Khamsi, Washington, DC

Healthy women should not rely on freezing their eggs as a way of
preserving their fertility, a leading US fertility organisation is
warning. Meanwhile, the largest study to date of children born from
frozen eggs suggests the procedure does not threaten child health as
feared.

Each frozen egg that is successfully thawed has only a 2% to 4%
chance of producing a live birth, say experts. Women are being
strongly warned against relying on this technique to postpone
motherhood by the American Society for Reproductive Medicine, which
issued new guidelines on Wednesday.

There is "extraordinarily limited" data on the rate of successful
pregnancies from egg freezing, said Marc Fritz, chair of the ASRM
expert committee issuing the warning at the society's annual meeting
in Washington, DC, US.

However, the results of a new study   released at the same meeting  
reviewing data about 550 children produced from egg freezing provides
some reassurance that the procedure does not carry an increased risk
of causing genetic damage leading to congenital abnormalities.
Ice damage

The study found that 1% of the infants conceived and born from frozen
eggs suffered from birth defects   a level comparable with that found
in the general population.

Human egg cells are between 10 and 15 times larger than other cells
in the body and so contain more water. As a consequence they
sometimes fail to survive being frozen because destructive ice
crystals form within the eggs as temperatures drop. To overcome this,
experts either cool down eggs very gradually in the so-called "slow
freezing" technique, or flash-freeze them in less than one second
using a process known as "vitrification".

The first child to be born from a frozen egg was in 1986, and since
then a number of changes to the procedure   including the manual
injection of sperm inside the egg, known as ICSI (intracytoplasmic
sperm injection)   have dramatically improved the chances of a live
birth from frozen eggs.

But not every egg survives the freezing and thawing process. And even
then, experts estimate that each successfully thawed egg has only a
2% to 4% chance of producing a live birth. The procedure is also
expensive   obtaining and freezing a dozen or so eggs costing about
$10,000 dollars. Patients must then pay to keep their eggs on ice,
and later spend further thousands of dollars on implantation.
Miscarriage risk

To address this concern, Ilan Tur-Kaspa, president of the Institute
for Human Reproduction in Chicago, Illinois, US, and colleagues
reviewed more than 100 published papers providing data on 750
pregnancies resulting in 550 live births from frozen eggs worldwide
since 1986.

Their review identified five babies with birth defects among the more
than 450 children for which health status was reported. The rate of
congenital abnormalities they found   0.9%   is comparable with that
seen among children conceived naturally, according to Tur-Kaspa.

The abnormalities observed among the children born from frozen eggs
include complications such as Turner syndrome and congenital heart
defects.

Tur-Kaspa notes that there is a miscarriage rate of about 20% among
women using frozen eggs. "It's within the range of what you see in in-
vitro fertilisation and ICSI" techniques, he says, noting that the
higher age of women opting for all of these procedures translates
into this miscarriage rate.

The ASRM committee stressed that while putting eggs on ice might be a
suitable option for cancer patients facing a risk of ovarian failure,
the technique should not be marketed to healthy women as a means to
defer childbearing.
"Egg trauma"

Fritz stresses that frozen eggs are "traumatised at least twice   by
freezing and by subsequent thawing", and that this means that the
procedure often fails to produce a viable embryo.

He worries that healthy women who elect to freeze their eggs have the
false impression that it ensures their chances of bearing a child
later on in life. He stresses that fertility centres need to explain
to patients that the procedure is highly experimental.

"Although significant research has been undertaken, and babies are
being born from these new techniques, caution and counselling are
imperative at this stage, and for several years to come," adds Simon
Fishel, managing director of the CARE Fertility Group, in the UK.


David Stodolsky    Skype: davidstodolsky

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