Embryo freezing
Freezing and storing embryos created during IVF so they can be used in a later cycle, avoiding repeat egg collection; success when they are used is still not guaranteed.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- Embryo freezing stores fertilised embryos from IVF for later use, avoiding repeat egg collection.
- Frozen embryo transfer success compares well with fresh transfer, but a baby is still not guaranteed.
- Because both an egg and sperm are involved, both providers must consent to how the embryos are used.
- Embryos are stored under UK rules with ongoing costs and consent renewal; check a clinic's verified data, not marketing.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Lets you try for pregnancy again without repeating egg collection
Where no good-quality embryos are available to freeze.
Laboratory work only — nothing for you to recover from. You are told how many embryos were frozen and stored.
A clear record of how many embryos were frozen and their grade.
Laboratory work only — nothing for you to recover from. You are told how many embryos were frozen and stored.
Your cycle is tracked, or medicines prepare the womb lining. Scans check the timing for thawing and transfer.
The embryo is thawed and placed in the womb in a few minutes. Mild cramping or light spotting can follow; you can...
You wait to take a pregnancy test at the time advised. This can be an emotionally demanding time.
What is embryo freezing?
Embryo freezing means freezing and storing embryos — eggs that have already been fertilised with sperm during IVF — so they can be used in a future cycle. The embryos are frozen quickly by a method called vitrification and stored in liquid nitrogen.
It is often done with embryos left over after a fresh IVF cycle, so you can try again later without going through egg collection again. Sometimes all the embryos are frozen and none transferred fresh — for example to let your body recover, to reduce the risk of OHSS, or to allow genetic testing. People also freeze embryos to preserve fertility before medical treatment, or before gender-affirming treatment.
When you are ready, an embryo is thawed and placed into the womb in a frozen embryo transfer (FET). Modern freezing is good, and many embryos survive thawing, with success rates that compare well with fresh transfers. But, as with all fertility treatment, a baby is not guaranteed: not every embryo survives the thaw, and not every transfer leads to a pregnancy.
Because an embryo is created from both an egg and sperm, both people who provided them have a say in what happens to it. Embryos are stored under strict UK rules, with storage costs and consent that must be renewed.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Fresh vs frozen embryo transfer
| Feature | Fresh transfer | Frozen transfer (FET) |
|---|---|---|
| Timing | Same cycle as collection | A later cycle |
| OHSS risk | Can be higher | Lower (body has recovered) |
| Success | Established | Comparable in many cases |
| Lets lining recover | No | Yes |
| Allows genetic testing first | Harder | Yes |
Whether a fresh or frozen transfer suits you depends on your response, OHSS risk and plans. This is a general comparison, not advice for your situation.
Preparing for your treatment
- Discuss how many embryos may be suitable to freeze and how they are graded.
- Understand that frozen embryo transfer is a separate later treatment with its own success chance.
- Complete consent forms carefully, including what should happen to the embryos if circumstances or relationships change.
- Be clear that both providers of the egg and sperm must agree to how the embryos are used or kept.
- Ask about storage length, ongoing storage costs and renewing consent.
- For a frozen transfer, ask whether it will be a natural cycle or use medicines to prepare the lining.
- Take folic acid and follow healthy-pregnancy advice ahead of a transfer.
What happens
Freezing happens in the laboratory during IVF. After eggs are collected and fertilised, embryos are grown for a few days. Suitable embryos are then frozen quickly by vitrification, which protects them from ice damage, and stored in liquid nitrogen. There is no procedure for you on the day of freezing.
When you decide to use a frozen embryo, the clinic times a frozen embryo transfer to your cycle. If you have regular periods, this may be done in a natural cycle using scans and hormone tests; otherwise medicines are used to prepare the womb lining.
On the day of transfer, the embryo is thawed and checked, then a fine soft tube is passed through the cervix to place the embryo into the womb. This takes only a few minutes and feels similar to a cervical smear. You can usually get up and carry on as normal, then wait to take a pregnancy test about two weeks later.
Is this treatment right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- Where no good-quality embryos are available to freeze.
- Where the egg and sperm providers cannot agree on consent for storage and use.
- Where a fresh transfer is clearly more appropriate for that person and cycle.
- Where someone expects a guaranteed baby from frozen embryos.
- Where a medical reason means pregnancy should be delayed or avoided.
Delay or rearrange if…
- You have an active infection or are unwell.
- The womb lining is not ready for a planned transfer.
- Consent forms are not complete or one provider is unsure.
- There is a possibility of OHSS after a recent egg collection, favouring a later frozen transfer.
- Important questions about storage, costs or future use are unresolved.
Alternatives to discuss
- Fresh embryo transfer in the same IVF cycle, where suitable.
- Egg freezing instead, if you prefer not to create embryos now.
- Donor embryos or donor gametes in the future, if needed.
- Choosing not to freeze and using all suitable embryos in the current cycle.
- Counselling to explore consent and future-use questions before deciding.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Benefits
- Lets you try for pregnancy again without repeating egg collection
- Allows a 'freeze-all' approach to lower OHSS risk or let the womb lining recover
- Makes genetic testing of embryos before transfer possible
- Can preserve fertility before treatment that may harm it
- Frozen embryo transfer success compares well with fresh transfer in many situations
Risks & complications
- No guarantee of a baby — not every transfer leads to a pregnancy
- Some embryos may not survive the thawing process
- Mild cramping or light spotting after a frozen embryo transfer
- Ongoing storage costs and the need to renew consent
- A transfer cancelled if an embryo does not survive thawing or the lining is not ready
- Disagreement between the egg and sperm providers about using the embryos
- Side effects from medicines used to prepare the lining
- Pelvic infection around the time of transfer
- An ectopic pregnancy (in the tube) after transfer
- Loss of stored embryos through a storage problem (clinics must have safeguards)
Embryo freezing itself is low-risk for you, because the demanding part (egg collection) happens earlier in IVF. The honest points are that not every embryo survives thawing, not every transfer succeeds, and — importantly — both providers of the egg and sperm must agree to how embryos are used. Ask your clinician about expected thaw survival, your realistic chance per transfer, and what happens to the embryos if your circumstances change.
Published figures to discuss
Frozen embryo transfer success depends on embryo quality, your age when the eggs were collected, and the womb lining. Modern vitrification gives good thaw-survival, and frozen-transfer success compares well with fresh in many cases, but figures vary by clinic and are reported in different ways. A clinic's own claims are not regulated like HFEA-verified data. The ranges below are cautious and general; ask for figures relevant to your situation and check verified data via the HFEA.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Embryo survival after thawing | High with modern vitrification, though not every embryo survives | Survival depends on embryo quality and the laboratory; ask your clinic's figures. | Guide sourcesClinical context |
| Live birth per frozen embryo transfer | Varies widely with age and embryo quality; comparable to fresh transfer in many cases | Per-transfer, age-dependent; use HFEA-verified, age-specific data rather than marketing. | Guide sourcesClinical context |
| OHSS with a frozen ('freeze-all') approach | Lower than fresh transfer because the body has recovered | A reason freeze-all may be advised when OHSS risk is high. | HFEA — Embryo freezinghfea.gov.ukSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no recovery from the freezing itself. A later frozen embryo transfer needs almost no recovery — most people carry on normally and wait about two weeks for a pregnancy test.
- No physical effects while embryos are simply in storage
- Mild period-type cramping or light spotting after a transfer
- Side effects from lining-preparation medicines, such as bloating, that settle
- Emotional ups and downs during the two-week wait
Aftercare
- After a transfer, carry on with normal activities; prolonged bed rest is not needed.
- Take any prescribed lining-support medicines exactly as directed.
- Take folic acid and follow healthy-pregnancy advice.
- Test for pregnancy only when the clinic advises, to avoid misleading early results.
- Keep your contact details up to date so storage consent for any remaining embryos can be managed.
- Budget for ongoing storage costs and note when consent needs renewing.
- Contact the clinic about heavy bleeding, severe pain, fever or feeling unwell.
- Number and grade of embryos frozen explained
- Consent forms completed, including future-circumstance choices
- Both providers' agreement on use confirmed
- Natural vs medicated transfer cycle discussed
- Storage costs and consent renewal understood
- Folic acid started ahead of transfer
⚠ Get urgent help if…
- Heavy vaginal bleeding (more than light spotting) after a transfer
- Severe or worsening tummy or pelvic pain
- A high temperature, chills or smelly discharge (possible infection)
- Sudden severe one-sided pain (possible ectopic pregnancy)
- Feeling faint or very unwell
- Severe headache, leg swelling or breathlessness while on hormone medicines (possible clot)
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
If you go on to a frozen embryo transfer, a good result is a single, healthy pregnancy. Frozen embryo transfer success compares well with fresh transfer in many situations, but a baby is not guaranteed — the embryo must survive thawing, implant, and develop.
How likely a transfer is to succeed depends on the embryo's quality, your age when the eggs were collected, and the womb lining. If a transfer does not work, any remaining frozen embryos can be used in further cycles. Compare clinics using the HFEA's verified data rather than marketing figures, and ask for results relevant to your situation.
Embryos can be stored for many years under UK law, but you must renew your consent at set intervals and keep your details up to date, or the embryos may have to be allowed to perish. Time in storage does not damage embryos. There are ongoing storage costs, and frozen embryo transfers each have their own cost, so it helps to plan ahead.
Related tests, treatments or support
Embryo freezing is part of IVF and connects to several other steps: blastocyst culture (growing embryos to day five before freezing or transfer), genetic testing of embryos, and later frozen embryo transfer. Some of these are routine and some are add-ons. Check any add-on against the HFEA's evidence ratings before paying extra.
Follow-up & long-term care
After freezing, you should be told how many embryos were stored and how they were graded, and given clear storage and consent information. The clinic should contact you about consent renewal. When you decide to use the embryos, a new plan for a frozen embryo transfer is made, with its own monitoring and follow-up.
- Keep your contact details up to date with the clinic.
- Renew storage consent within the required time so embryos are not lost.
- Budget for ongoing storage fees and the cost of each frozen embryo transfer.
- Keep both providers' wishes and consent current, especially if circumstances change.
- Re-check HFEA add-on ratings before any future treatment cycle.
Repeat, follow-on and what comes next
- Not every frozen embryo survives thawing, so a transfer can occasionally be cancelled.
- A negative transfer can be followed by further transfers using any remaining embryos.
- Lining-preparation protocols may be adjusted between cycles.
- Plans may change over the storage period, and consent must be actively renewed.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- A clear record of how many embryos were frozen and their grade.
- Written information on storage, ongoing costs and consent renewal dates.
- A named contact for concerns after a transfer.
- A clear plan for using any remaining embryos if a transfer fails.
- A reminder system so consent is renewed and embryos are not lost.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- Whether freezing is part of an existing IVF cycle or a fertility-preservation cycle
- The number of embryos frozen and stored
- Ongoing storage fees, charged over years
- The cost of each later frozen embryo transfer
- Medicines used to prepare the womb lining for transfer
- Any genetic testing of embryos chosen before freezing
- Counselling and consent processes
- Whether freezing is included in your IVF package or charged separately
- Annual or ongoing storage charges and how long they apply
- The cost of a later frozen embryo transfer
- Medicines needed for a frozen transfer cycle
- What happens to fees if no embryos are suitable to freeze
- Consent renewal arrangements and any associated cost
- Cancellation and refund policies
On the NHS? Embryo freezing may form part of NHS (or HSC in Northern Ireland) or private IVF. Funding and eligibility rules are set separately in England, Scotland, Wales and Northern Ireland and can differ between local areas — national clinical guidance such as NICE's is not a guarantee of NHS funding, and the rules can change. Ongoing storage and later frozen embryo transfers can also carry their own costs and criteria. Ask the relevant NHS/HSC fertility service or your clinic to confirm your current eligibility before you start.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not making clear that both providers must agree to how embryos are used.
- Selling frozen transfer as a guaranteed route to a baby.
- Unclear information on storage length, ongoing costs and consent renewal.
- Not discussing what happens to embryos if circumstances or relationships change.
- Adding embryo add-ons without explaining their evidence and cost.
Marketing red flags
- Implying frozen embryos guarantee a future baby.
- Quoting success rates without making clear they are per transfer and age-dependent.
- Hidden or escalating storage fees.
- Pushing genetic-testing or other add-ons without clear evidence for your case.
- Marketing figures that are not the clinic's HFEA-verified data.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- How many embryos are suitable to freeze, and how are they graded?
- What is the expected chance an embryo survives thawing, and my chance per transfer?
- Would you advise a fresh transfer or freezing all embryos, and why?
- What are the storage costs and consent rules, and what happens if we don't renew?
- What happens to our embryos if our circumstances or relationship change?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my treatment, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this treatment not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Are frozen embryos as good as fresh ones?
How long can embryos be stored?
What happens to our embryos if we separate?
Will the NHS pay for embryo freezing and frozen transfers?
Do I need to rest after a frozen embryo transfer?
Why might all my embryos be frozen rather than transferred fresh?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: HFEA — Embryo freezing HFEA — In vitro fertilisation (IVF) HFEA — Choose a Fertility Clinic (verified success rates) RCOG — Ovarian hyperstimulation syndrome (patient information) NHS — IVF NICE NG257 — Fertility problems (clinical guidance, England) NHS inform (Scotland) — Infertility and access to treatment NHS Wales — Specialist fertility services commissioning policy (CP38) Northern Ireland — Regional Fertility Centre (Belfast Trust)
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
Related guides: Egg freezing · Blastocyst culture · Ovulation induction · Assisted hatching · Egg donation / using donor eggs