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Elective freeze all cycles
For most patients, having a routine cycle of proven fertility treatment is effective without using any treatment add-ons.
Our ratings indicate whether the evidence from studies shows that a treatment add-on is effective at improving treatment outcomes for someone undergoing fertility treatment. Our ratings do not tell you how much that treatment add-on improves your chances of having a baby – please discuss this with your clinic.
What is an elective freeze all cycle?
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.
Elective freeze all cycles can be used routinely to reduce a patient’s chances of developing ovarian hyperstimulation syndrome (OHSS).
| Rated outcomes for elective freeze all cycles | |
|---|---|
| Rated amber for increasing the chances of having a baby for most fertility patients
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For most fertility patients elective freeze all is rated amber because it is not clear whether this add-on is effective at improving the chances of having a baby. This is because there is conflicting moderate/high quality evidence – in some studies the add-on has been found to be effective, but in other studies it has not. |
| Rated green for reducing risk of ovarian hyperstimulation syndrome (OHSS) in most fertility patients
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Freeze all cycles are proven to be effective at reducing the risk of developing OHSS for most fertility patients. Find out more about OHSS and the risks of fertility treatment. |
| Rated green for reducing risk of OHSS in patients with an increased risk of OHSS
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Freeze all cycles are proven to be effective at reducing the risk of developing OHSS for patients with an increased risk of getting OHSS. |
| Rated grey for reducing the risk of adverse obstetric/neonatal outcomes for most fertility patients
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We cannot rate the effectiveness of this add-on at reducing the risk of adverse obstetric/neonatal outcomes for most fertility patients as there is insufficient moderate/high quality evidence. |
| Rated grey for reducing the risk of adverse obstetric/neonatal outcomes for populations at increased risk of OHSS
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We cannot rate the effectiveness of this add-on at reducing the risk of adverse obstetric/neonatal outcomes for populations at increased risk of OHSS as there is insufficient moderate/high quality evidence. |
| Rated grey for increasing the chances of having a baby for populations at increased risk of OHSS
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We cannot rate the effectiveness of this add-on at improving the chances of having a baby for populations at increased risk of OHSS as there is insufficient moderate/high quality evidence. |
Specific safety concerns about a treatment add-on, including those discussed above, are included under the dedicated section Is this treatment add-on safe?.
What do the ratings mean?
There are five ratings that indicate whether a treatment add-on is effective at improving treatment outcomes for someone undergoing fertility treatment, according to the evidence from studies. To make it easier to understand the scientific evidence for each treatment add-on we have a range of symbols and colours for each rated add-on below.
Green traffic light
On balance, findings from high quality evidence shows this add-on is effective at improving the treatment outcome.
Yellow traffic light
On balance, it is not clear whether this add-on is effective at improving the treatment outcome. This is because there is conflicting moderate/high quality evidence – in some studies the add-on has been found to be effective, but in other studies it has not.
Grey traffic light
We cannot rate the effectiveness of this add-on at improving the treatment outcome as there is insufficient moderate/high quality evidence.
Black traffic light
On balance, the findings from moderate/high quality evidence shows that this add-on has no effect on the treatment outcome.
Red traffic light
There are potential safety concerns and/or, on balance, findings from moderate/high quality evidence shows that this add-on may reduce treatment effectiveness.
All treatment add-ons on our list will have a rating to indicate whether the evidence shows that the treatment add-on is effective at improving the chances of having a baby for most fertility patients. Some treatment add-ons on our list may also have additional ratings for specific treatment outcomes. For example, whether the evidence shows that the treatment add-on reduces miscarriage. There may also be further ratings for specific patient groups, for example whether the evidence shows that the treatment add-on is effective for those who are aged over 40. Please see the individual webpages for each treatment add-on for their ratings.
An agreement between the HFEA and other professional and patient bodies (the 19th October 2023 consensus statement) stated that treatments that have no strong evidence of their safety and/or effectiveness should only be offered in a research setting. Patients should not be charged extra to take part in research, including clinical trials.
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 frozen embryo transfer (FET) cycles it is higher. This increased risk of large for gestational age babies along with an increased risk of hypertensive disorders such as pre eclampsia, means there needs to be caution before moving to a freeze all policy for all patients.
Some research suggests that the chances of having a baby are increased by using FET rather than fresh transfers. Currently, doctors don’t know with enough confidence whether freeze all cycles are more effective than conventional IVF or ICSI at increasing your chances of having a baby. However, there is no evidence that freeze all cycles decrease your chances of having a baby.
At the July 2023 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 are available on the SCAAC webpage. The list of studies reviewed can be found under the section titled ‘Studies reviewed for this treatment add-on’.
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 not all the frozen embryos will 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.
Studies reviewed for this treatment add-on
The SCAAC have reviewed the following studies for freeze all cycles:
| General: | Aflatoonian 2010 | 10.1007/s10815-010-9412-9 |
| Shapiro 2011a | 10.1016/j.fertnstert.2011.05.050 | |
| Shapiro 2011b | 10.1016/j.fertnstert.2011.02.059 | |
| Shapiro 2015 | 10.1016/j.fertnstert.2015.07.1141 | |
| Magdi 2017 | 10.1016/j.fertnstert.2017.04.020 | |
| Shi 2018 | 10.1056/NEJMoa1705334 | |
| Le 2018 | 10.1093/humrep/dey253 | |
| Vuong 2018 | 10.1056/NEJMoa1703768 | |
| Vuong 2019 | 10.1016/j.rbmo.2018.12.012 | |
| Wei 2019 | 10.1016/S0140-6736(18)32843-5 | |
| Stormlund 2020 | 10.1136/bmj.m2519 | |
| Simón 2020 | 10.1016/j.rbmo.2020.06.002 | |
| Boynukalin 2020 | 10.1371/journal.pone.0234481 | |
| Li 2021 | 10.3389/fendo.2021.730059 | |
| Wong 2021 | 10.1093/humrep/deaa305 | |
| Maheshwari 2022 | 10.1093/humrep/deab279 | |
| Maheshwari 2022a | 10.3310/AEFU1104 | |
| OHSS risk: | Chen 2016 | 10.1056/NEJMoa1513873 |
| Ye 2018 | 10.1186/s12958-018-0373-7 | |
| Deng 2019 | 10.1007/s11596-019-2031-5 | |
| Shrem 2019 | 10.1016/j.rbmo.2019.04.014 | |
| Santos-Ribeiro 2020 | 10.1093/humrep/deaa226 | |
| Deepika 2021 | 10.5935/1518-0557.20200028 | |
| Huang 2021 | 10.1038/s41598-021-02227-w | |
| Vuong 2021 | 10.1007/s10815-021-02180-7 |
What are treatment add-ons?
In vitro fertilisation (IVF) and intrauterine insemination (IUI) are established treatments that have been proven effective for most patients. Treatment add-ons are optional non-essential treatments that may be offered in addition to such proven fertility treatment. The HFEA provides information on add-ons that meet the following criteria:
- Additional treatments (to the core treatment e.g. IVF or IUI) that are being offered to the general patient population in licensed fertility clinics in the UK,
- Where there is published scientific literature which claims to demonstrate that the add-on improves live birth rates or other treatment outcomes rated by the HFEA; but
- where evidence of effectiveness for the use of the treatment in a clinical setting is lacking or absent; and
- where patients need unbiased information about the effectiveness and risks of this treatment
It is important to keep in mind that for most patients, having routine cycles of proven fertility treatment are effective without using any treatment add-ons. If you are paying for your own treatment, you may want to think about whether it might be better to pay for multiple cycles of IVF or IUI, rather than spending large sums of money on a single treatment cycle with treatment add-ons that haven’t been proven to be effective.
We aim to publish clear and reliable information about some of the treatment add-ons that don’t have enough evidence to show that they improve your chances of having a baby and other relevant treatment outcomes. This provides useful information to patients and allows them to question the use of add-ons.
Review date: 19 October 2025
