With the increasing frequency of couples using In Vitro Fertilisation in order to conceive, some degree of caution should be given in relation to the eggs, sperm or embryos stored for these purposes and the effect a subsequent separation, divorce or even death may have.
The law and consent
The relevant legislation is the Human Fertilisation and Embryology Act 2008 which has as its primary aim the regulation of the creation, storage and use of all human embryos created outside the body.  The issue of “consent” underpins much of the Act.  “Consent” is dealt with in Schedule 3 of the Act.  There are different rules in relation to the consent to the storage of gametes (a gamete is a single egg or a single sperm) and embryos but it is quite straight forward.  In relation to gametes, the consent must be given by the supplier of the gamete, being one individual.  In relation to embryos, being an egg fertilised by a sperm, consent must be given by both suppliers of the gametes, so two individuals.  Consent is obtained by the IVF clinic during the IVF process and usually covers consent to create an embryo, consent to the storage of eggs, sperm or embryos for a set period of time (which must be renewed at the end of the period), and consent to the use of the eggs, sperm or embryos in the event of the death of either person.  Importantly, an individual can withdraw their consent to storage of the gamete or embryo at any time prior to its use.  Also, importantly, both parties must provide their consent to the thawing and use of the embryo at the time that is to be done, and consent is not provided in advance for this procedure (other than in the case of death of one of the parties). 
Gamete or embryo? 
Gametes and embryos are stored for a number of different reasons and purposes.  For some people the issue of gamete storage is raised when they are about to undergo treatment which may destroy their gametes such as cancer treatment, the removal of ovaries, or the removal of testes.  In the vast majority of cases gametes and embryos are stored when couples embark on IVF treatment, which relies firstly on the collection of the gametes from the couple.  It is often recommended that rather than the gametes themselves being stored, several embryos are created from the gametes and those embryos are stored, because embryos tolerate the freezing conditions of the storage better than gametes and therefore the implantation of a thawed embryo in the future is more likely to lead to a live birth than the attempted fertilisation of a thawed egg with a thawed sperm.   
While it seems perfectly sensible to maximise the chances of successful impregnation at a time when both individual’s interests are aligned in the creation of a new life for their family, it does cause problems further down the line if things take a different turn and if one of the individuals decides to remove their consent to the ongoing storage or use.  Both parties require to consent to the continued storage or use of an embryo.  During the storage process, either party can at any time remove their consent to the storage of their own gametes or embryos created using their gametes.  If that happens, the embryos will eventually be destroyed.  Should a woman not have stored her own gametes, and only have stored embryos created using her gametes, the destruction of the embryos may be mean she will never give birth to her own child.  This could be potentially another devastating blow for a woman also contemplating the end of her relationship.  This situation arose in the very high profile case of Natalie Evans in 2007.  Ms Evans embarked on fertility treatment after she was diagnosed with ovarian cancer in 2001.  Five embryos were created and then frozen using eggs removed from her and fertilised with her partner’s sperm. Shortly thereafter, she and her partner separated and he withdrew his consent to the continued storage or use of the embryos.  Ms Evans petitioned the High Court in England for an order allowing her to use the embryos without her partner’s consent.  She was unsuccessful and was also unsuccessful on appeal to the English Court of Appeal and the European Court of Human Rights.  While there is obviously a degree of sympathy to Ms Evan’s situation, which will mean she can never bear children of her own, this decision must be the sensible one. 
Two cases decided in the latter part of 2018 also raise some interesting points.  In ARB v IVF Hammersmith and R [2018] EWCA Civ 2803, the issue of consent was raised in slightly different circumstances.  ARB and R were in a relationship together and had previously gone through IVF treatment resulting in the birth of their son and the creation, freezing and storage of several more embryos.  The couple required to consent to the continued storage on an annual basis.  In 2010 the couple separated.  R forged ARB’s signature on a consent form authorising the IVF to thaw and implant one of the embryos into R resulting in the birth of a daughter.  ARB had not consented to the thawing or implantation of the embryo.  ARB sued the clinic on the basis of a breach of contract for the costs involved in bringing up his daughter. A finding of breach of contract was made by the Court on the basis that the clinic failed to obtain his consent but the Court refused to award him compensation on public policy grounds since healthy children are a blessing (this was already established in law of negligence, but this case determined that the same applies for contractual claims). 
The death of a loved one could also have disastrous consequences.  The case of Y v A Healthcare NHS Trust and Others [2018] EWCOP 18 involved a young couple who already had a son together and were in the process of IVF treatment in order to conceive a second child.  Prior to the completion of the treatment, and prior to the parties’ gametes being collected for that purpose, the husband was involved in a road traffic accident resulting in a catastrophic brain injury from which he would ultimately die.  Before his death his wife wished for his sperm to be collected and stored for the purposes of the IVF treatment they had already embarked upon, despite the fact he did not have capacity and therefore could not consent to such a procedure.  There was evidence from the wife that the couple had discussed the storage and use of their gametes should one of them die and that the husband was happy for his sperm to be used should he die.  She petitioned the Court who granted her order, declaring it to be both lawful and in his best interests that his sperm be collected, stored and used for this purpose despite his imminent death.  The Court ordered that a family member (not the wife) could consent to the storage and use of the husband’s sperm on his behalf.  This is contrasted with the high profile case of Diane Blood in 1997.  Ms Blood petitioned the court to allow her to use her husband’s sperm (which had been collected shortly before his death) in IVF treatment.  The Court refused to allow her to use the sperm in a UK clinic because her husband had not consented to it, but said it would be a breach of EU law to prevent her using the sperm in another country within the EU.  She subsequently travelled to Belgium for treatment.  Perhaps the difference between the two cases is the lack of evidence of the husband’s wishes in respect of the use of his sperm, and his wishes in relation to IVF itself.
What to do? 
For clear public policy reasons, the issue of consent is an important one.  It is also foreseeable that a male partner may not wish for his ex to fall pregnant with his biological child after the parties have separated.  For those reasons, thought really should be had to what both parties’ may wish for the future should their relationship breakdown.  It may be better from a legal perspective to store gametes (which only require the individual’s supplier’s consent) to avoid the risk the embryos are destroyed due to the withdrawal of one party’s consent.