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Elective freeze all cycles

Treatment add-on

Elective freeze all cycles is rated amber

Elective freeze all cycles is rated amber


What does this traffic light rating mean?

The traffic light rating system consists of three colours that indicate whether the evidence, in the form of high-quality randomised control trials (RCTs), shows that a treatment add-on can safely improve the live birth rate for someone undergoing fertility treatment.

We give an amber symbol for an add-on where there is conflicting evidence to show that an add-on can improve live birth rates, or that the add-on is safe for patients to use. This means that the evidence is not conclusive and further research is required, and the add-on should not be recommended for routine use.

What is elective freeze all cycles?

In a normal IVF cycle, one to two fresh embryos are transferred a few days after the egg collection and any remaining suitable embryos are frozen.

Elective freeze all cycles involve creating embryos using IVF or ICSI and then choosing to freeze them all so no embryos are transferred in the ‘fresh’ cycle. The embryos are thawed a few months later and transferred to the patient’s womb as part of a frozen embryo transfer (FET) cycle.

There is some evidence that the body’s hormonal response to fertility drugs can affect the lining of the womb, which makes it more difficult for the embryos to implant. Freezing the embryos means they can be transferred back into the patient when the womb lining is well developed.

It’s also thought by having all their embryos frozen, women are at lower risk of suffering from ovarian hyperstimulation syndrome (OHSS), an overreaction to fertility drugs. This is because OHSS is more common and more severe when it occurs during a pregnancy.

Find out more about OHSS and the risks of fertility treatment

There is also evidence that while the birthweight of babies born from normal fresh IVF cycles is lower, from FET cycles it is higher, closer to naturally conceived babies. Since birthweight is associated with risk of disease in later life, freeze all cycles may be safer for the baby.

Are there any risks?

The freezing process is generally thought to be safe for the embryo, although there’s always a risk that one or more embryos may not survive.

What’s the evidence for freeze all cycles?

At the October 2019 Scientific and Clinical Advances Advisory Committee (SCAAC) meeting the Committee evaluated the evidence base for elective freeze all cycles. Minutes of the October 2019 discussion and the evidence used to inform this discussion are available here.

Research into freeze all cycles is progressing quickly. Some research suggests that pregnancy rates are increased by using frozen embryo transfers (FETs) rather than fresh transfers, and that the risks to mother and baby are lower. These include the risk of OHSS (above) and of low birthweight. Currently, doctors don’t know with enough confidence whether freeze all cycles are safer and more effective than conventional IVF or ICSI.

What are treatment add-ons?

Treatment add-ons are optional additional treatments that you may be offered on top of your routine fertility treatment, often at an additional cost. Some clinics may refer to treatments add-ons as ‘supplementary’ or ‘embryology treatments’. There are a wide range of treatment add-ons on offer including tests, drugs, equipment, holistic or alternative therapies, and surgical interventions.

However, all treatment add-ons share one common characteristic: they claim to improve the chances of having a baby (live birth rate). Evidence on whether some treatment add-ons are safe or effective is often missing or absent. These claims can attract a lot of attention with many patients opting for a treatment add-on thinking that it may be the best option for them despite there being little or no evidence to prove it is.

Treatment add-ons have varying levels of scientific evidence to support their effectiveness and safety and, at times, this evidence can be contradictory. It is important to keep in mind that for most patients, routine fertility treatment is an effective option on its own.

We aim to publish clear and reliable information about some of the treatment add-ons that lack sufficient evidence to show that they are effective and/or safe. This allows patients to make an informed decision about whether using a treatment add-on as part of their treatment is the best option for them.

To make it easier to understand the scientific evidence for each treatment add-on we have developed the HFEA’s traffic-light rated list of add-ons.


Review date: 25 August 2022

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