There are currently at
least 100,000 'spare' human embryos stored in freezers across
the European Union.
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These embryos were created as a routine
part of infertility treatment (IVF). A single round
of IVF treatment usually involves fertilising many eggs
at the same time. Several fertilised eggs are then re-implanted
into the mother, and the rest are frozen in case the
first attempt to achieve pregnancy doesn't work.
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If the IVF couple gets pregnant immediately, they may choose
not to use their remaining embryos. In some countries couples
have the option of either donating unwanted embryos for research
or discarding them.
For some stored embryos, however, decisions about their
fate were never made. Over the past 20 years since IVF began,
many of the egg and sperm donors have changed their address,
got re-married and changed their name or perhaps even died.
Fertility clinics may be unable to trace them. The fate of
many stored embryos is thus uncertain.
A second and even more controversial source of embryos to
provide stem cells would be embryos created purely for research
or treatment. There has never been any intention of implanting
them into a woman. Creating an embryo for this purpose is
considered by many people (and some governments) to be ethically
wrong.
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Nevertheless, there are millions of
sperm and thousands of unfertilised eggs already in
freezers in IVF clinics across Europe. If the sperm
were used to fertilise the eggs, there would be even
more embryos to supply stem cells to cure disease.
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There is one final way of obtaining human embryos - using
the cloning technique. This involves making a human embryo
that contains the entire genetic make-up of someone who is
already alive. If implanted into a woman's womb, the embryo
could theoretically grow into a clone (a genetically identical
copy) of that person. If used in research, the embryo could
provide stem cells to cure disease.
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