What is embryo freezing and
During in vitro fertilisation (IVF) or intra-cytoplasmic
sperm injection (ICSI) treatment, fertility drugs are used to
stimulate the ovaries to produce more eggs than usual. These are
then fertilised with your partner's, or a donor's sperm to create
Because there is normally a number of unused embryos, some
people choose to freeze the good quality unused embryos for use in
later treatment cycles or for donation.
Is embryo storage for
You may consider freezing your unused embryos for the following
- It gives you the option of using the embryos in future IVF or
ICSI cycles, without having to go through the risks, expense and
inconvenience of using fertility drugs and undergoing egg
- If your treatment needs to be cancelled after egg collection
(for example, if you have a bad reaction to fertility drugs), you
may still be able to store your embryos for future use.
- You want to donate your unused embryos for the treatment of
other women or for research.
- You are facing medical treatment, such as for cancer, that may
affect your fertility, (embryo freezing is currently the most
effective way for women to preserve their fertility).
How much control do I have over what happens to
Before the storage process begins, we will ask you to sign
consent forms. The forms allow you to specify:
- How long you want the embryos to be stored (the standard period
is ten years).
- What should happen to your embryos if you or your partner were
to die or become unable to make decisions for yourself.
- Whether the embryos are to be used for your own treatment only,
or whether they can be donated for someone else's treatment, or
used for research.
- Any other conditions you may have for the use of your
You, your partner or the donor(s) can vary or withdraw
consent at any time, either before treatment or before the embryos
are used in research. It is important to understand that, if this
happens, your embryos will not be used in treatment or
If one person withdraws consent (either the person who
provided the eggs or the sperm) then there will be a 'cooling-off'
period of up to a year which will allow you to decide what should
happen to the embryos.
If you are not continuing treatment, you may want to
consider donating your unused embryos.
What is my chance of having a baby using frozen
Due to the freezing and thawing process, your chances of
having a baby using a thawed frozen embryo are lower than with a
Your chances of becoming pregnant with a thawed frozen
embryo are not affected by the length of time the embryo has been
What are the risks of freezing
- Not all embryos will survive freezing and eventual thawing when
they come to be used. Very occasionally no embryos will
- It is not uncommon for those embryos that do survive freezing
and thawing to lose a cell or two. Ideally the embryos should
continue to divide between thawing and transfer.
- As embryo transfer is involved in using frozen embryos, the
same risks apply.
To date, there is no known evidence to suggest a risk to
patients or to children born from frozen embryos. The Human
Fertility and Embryology Authority (HFEA) will continue to review
the evidence available on embryo freezing and the long-term results
of frozen embryo transfer.
All patients undergoing this process are advised to access our
Counselling Service, as it can
be particularly helpful at this time.
How are donated frozen embryos
Your embryos can only be donated if the people who
provided the sperm and eggs which were used to create the embryos -
you, your partner (if you have one) and any donor(s) - give their
consent to this in writing. Once you have given your consent, they
may be used for three purposes:
- In another person's fertility
If you donate your embryos to another person to be used in
treatment, the same rules on donation apply as to donating sperm or
eggs. You will both need to have further screening tests for cystic
fibrosis, karyotype (chromosome analysis), cytomegalovirus,
syphilis and gonorrhoea. In addition your blood groups will
Any child born from your donation will be able to find out
identifying information about you when they reach the age of 18. For more information, click here.
If you are donating embryos to a single woman who has
agreed to have parental responsibility, the sperm donor may be
regarded as the legal father of the child. It is therefore very
important that you fully discuss this aspect with your consultant.
You may need to consider obtaining legal advice over
If you donate your embryos to research, they could be used in
studies, such exploring IVF technology, or in stem cell studies. For more
information on research projects currently licensed by the HFEA,
If you donate your embryos to training, they could be used
by trainee embryologists in order to practise techniques such as
freezing embryos and removing cells from embryos.
note: It is important that all couples with frozen embryos
stored at Saint Mary's Hospital inform us about any changes in
their contact details. This is because we are required by law
to contact you regarding the continued storage of your embryos for
the consented period.
For more information please visit the HFEA