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Elective freeze all cycles

Treatment add-on with limited evidence

For most patients, having a routine cycle of proven fertility treatment is effective without using any treatment add-ons.


Elective freeze all cycles is rated amber because there is conflicting evidence from randomised controlled trials (RCTs) to show that it is effective at improving the chances of having a baby for most fertility patients.

What does this traffic light rating mean?

Our traffic-light rated list of add-ons consists of three colours that indicate whether the evidence, in the form of high-quality RCTs, shows that a treatment add-on is effective at improving the chances of having a baby for most fertility patients. 

We give an amber symbol for an add-on where there is conflicting evidence from RCTs to show that an add-on is effective at improving the chances of having a baby for most fertility patients. This means that the evidence is not conclusive and further research is required, and the add-on should not be recommended for routine use.

Our traffic light ratings only indicate the effectiveness of a treatment add-on, at improving your chances of having a baby. Specific safety concerns about a treatment add-on are included under the dedicated section ‘Is this treatment add-on safe?’.

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.

What’s the evidence for freeze all cycles?

Research into freeze all cycles is progressing quickly. 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.

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.

Some research suggests that the chances of having a baby 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 ovarian hyperstimulation syndrome (OHSS) 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 at increasing your chances of having a baby.

At the October 2020 Scientific and Clinical Advances Advisory Committee (SCAAC) meeting the Committee evaluated the evidence base for elective freeze all cycles. Minutes of this discussion and the evidence used to inform this discussion are available on the SCAAC webpage.

The use of freeze all cycles for specific medical reasons

Add-ons may be offered for reasons other than to improve the chances of having a baby and in some specific circumstances there may be a justifiable medical reason for using the add-on as part of fertility treatment.

Freeze all cycles are proven to be effective at reducing ovarian hyperstimulation syndrome (OHSS) in certain groups of patients. Therefore, it could be used appropriately for specific clinical cases after careful discussion with a clinician.

Find out more about OHSS and the risks of fertility treatment

Is this treatment add-on safe?

Elective freeze all cycles do not carry any known risks for the person undergoing fertility treatment. However, there’s always a risk that one or more embryos may not survive.

If you have any questions about the safety and risks, your clinic will be able to discuss whether a treatment add-on would be safe for you to use considering your specific medical history and circumstances.

What are treatment add-ons?

  • optional additional treatments, also referred to as ‘supplementary’, ‘adjuvants’ or ‘embryology treatments’.
  • often claim to be effective at improving the chances of having a baby (live birth rate) but the evidence to support this for most fertility patients is usually missing or not very reliable.
  • likely to involve an additional cost on top of the cost of a routine cycle of proven fertility treatment. Some treatment add-ons can cost hundreds or thousands of pounds each.

It is important to keep in mind that for most patients, having a routine cycle of proven fertility treatment is effective without using any treatment add-ons. If you are paying directly for your own treatment, you may want to think about whether it might be more effective and/or affordable to pay for multiple routine proven treatment cycles, rather than spending large sums of money on a single treatment cycle with treatment add-ons that haven’t been proven to be effective at increasing the likelihood of you having a baby.

We aim to publish clear and reliable information about some of the treatment add-ons that don’t have enough evidence, from high-quality randomised control trials (RCTs), to show that they are effective at improving your chances of having a baby.

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


Review date: 19 April 2023

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