Frozen Embryo Transfer
A frozen embryo transfer, usually shortened to FET, is the second half of an IVF cycle done on its own. An embryo frozen after an earlier collection is thawed, checked, and placed in the uterus through a fine catheter. There is no stimulation, no collection and no anaesthetic. The transfer itself takes about ten minutes.
Freezing used to be where the spare embryos went. It is now where most transfers happen, and for good reason. Separating the collection from the transfer lets the uterus be dealt with on its own terms. No ovaries full of follicles, no stimulation hormones still washing through, no rush to decide anything in the four days after a collection.
Freezing itself now loses very few embryos. Vitrification, where the embryo is cooled so fast that ice never forms in it, replaced the old slow freezing about fifteen years ago. Blastocyst survival through the warming is now generally reported at ninety per cent or more. Slow freezing lost a good deal more than that, which is why older figures comparing fresh and frozen read so differently.
So the live question on this page is not fresh against frozen. It is which kind of frozen cycle you have. One the clinic drives with hormone tablets and pessaries, or a natural one that follows your own ovulation. Both work well, and the right one depends on your own cycles, so I would talk it through with your clinic.
At a glance
- Also known as
- frozen embryo transfer, FET, frozen-thawed embryo transfer, freeze-all cycle
- Appointment time
- 10–15 minutes for the transfer; 2–4 weeks for the cycle around it
- Back to normal
- Same day
- Typical cost
- $4,000–$7,000 per transfer (United States, self-pay)
- Usually preceded by
- IVF
Figures reviewed .
On this page
Who it’s for
Anyone with embryos in storage. That is most people who have done IVF. A collection that goes well makes more than one usable embryo, and only one goes back at a time. A batch of four is four attempts from one set of injections.
The other group is people whose clinic planned to freeze everything from the start. Freeze-all is a deliberate strategy, not a fallback. It is chosen when the ovaries have responded hard and a fresh transfer would risk hyperstimulation. Also when progesterone rises too early, when embryos are being tested and the results will not come back in time, and when the lining needs sorting out first.
Freeze-all is often decided partway through stimulation, so it helps to know the term in advance. It is a positive plan, not a setback.
Which cycle type suits you follows from your own cycles. Ovulate regularly and predictably, and a natural or modified natural cycle is available to you. If your cycles are absent or hard to track, if a gestational carrier is involved, or if the date has to be fixed, the medicated route is the practical one.
Eligibility is mostly about the uterus and the paperwork. Clinics check the lining and the shape of the cavity, set a BMI range, and want your storage consents in date. Keep an eye on your storage consent dates yourself, as they need renewing to stay valid. See eligibility across fertility treatment.
Before your collection cycle starts
Ask whether the clinic expects to freeze everything, and what would make them change their mind. Knowing that a freeze-all is likely means the news halfway through stimulation is simply the plan you already agreed to.
How it’s done
Everything begins with the lining. An embryo will only implant into a uterus at the right point in its own cycle, and there are two ways to reach that point. Your clinic almost certainly has a preference.
A medicated cycle, sometimes called hormone replacement, takes the decision away from your ovaries. Oestrogen as tablets or patches for roughly two weeks, then a scan to check the lining has thickened past about seven millimetres. Then progesterone, as pessaries or injections, to open the implantation window. The transfer is booked a fixed number of days after the progesterone starts. Predictable, and it works whether you ovulate or not.
A natural cycle does the opposite. The clinic tracks your own follicle with scans and tests for the surge that triggers ovulation, and the transfer lands five to seven days later. A modified natural cycle adds a trigger injection to pin the timing down, and often some progesterone support. Fewer drugs, and your own corpus luteum supports the early weeks. The medicated version has to do that job with pessaries.
Thaw day is the embryologist's, not yours. The embryo is warmed, rehydrated and left to recover for an hour or two before it is graded again. Most look the same as they did going in.
The transfer is undramatic. You arrive with a full bladder, which straightens the angle for the ultrasound. A speculum goes in, and a fine catheter carries the embryo through the cervix under scan guidance. A few minutes, no anaesthetic, no bed rest, and you walk out.
One embryo, in almost all cases. Elective single embryo transfer became standard because two raise the chance of twins far more than the chance of a baby.
When the transfer date is being set
Ask which kind of cycle they are putting you on and whether your own ovulation could be used instead. Both are reasonable, so the useful thing is hearing their reasoning, so you understand the plan from the start.
After frozen transfer
There is nothing to recover from. People go back to work the same afternoon. The odd thing about a frozen transfer is how little marks the most consequential ten minutes of the whole treatment. Some cramping, a little spotting from the speculum, and that is the physical story.
What you feel instead is the progesterone. Bloating, sore breasts, tiredness, a mood that dips. All of it imitates early pregnancy well enough to be useless as a sign either way. Pessaries are messy, and injections sting and leave lumps. Keep taking them exactly as prescribed until the clinic tells you to stop; that is the one thing entirely in your hands here.
Then the wait, which most people find the hardest stretch to sit through. No monitoring, nothing to do, nothing to control. Call the clinic rather than sitting on it if you have heavy bleeding, one-sided pain or a fever. Keep the out-of-hours number somewhere you can find it at two in the morning.
| 2–3 weeks before | Cycle starts. Oestrogen on a medicated plan, or scans and surge tests on a natural one. |
|---|---|
| Lining scan | A check that the lining has thickened enough. Occasionally the cycle is paused here and restarted. |
| Thaw morning | The embryo is warmed and graded, and the clinic rings to confirm the transfer is going ahead. |
| Transfer day | Ten minutes with a full bladder, no anaesthetic. Back at your desk the same afternoon if you want to be. |
| Days 1–9 after | Progesterone continues without a break. No scans, no bloods, nothing to report. |
| Days 9–14 | A blood test for hCG. Home tests before this are unreliable, so the blood test is the one to wait for. |
| Weeks 6–7 | A first scan if the test was positive. Progesterone often carries on into the first trimester. |
On transfer day
Write the progesterone plan down on paper, doses and times, before you leave the clinic. It usually runs for weeks, sometimes changes after the blood test, and it is the one part of this you are entirely in charge of.
Risks and complications
The risk specific to this page is that there is nothing to transfer on the day. An embryo can fail to survive the thaw. It is uncommon now, and when it happens the clinic can usually warm another from the same batch. Cycles are also cancelled for a lining that will not thicken. Neither outcome means the next attempt will go the same way.
There is no hyperstimulation risk here, because nothing is stimulating your ovaries. That is one of the arguments for freezing everything, and the clearest safety gain in this whole area.
One point concerns the cycle type. Registry data and some trials point to a higher rate of high blood pressure in pregnancy, pre-eclampsia included, after medicated transfers than after natural ones. The suggested explanation is the missing corpus luteum and the hormones it would have made.
This is still being studied: the size of any difference is unsettled and the studies do not all agree. It is no reason to avoid a medicated cycle when your own cycles need one, and simply a good reason to ask which you are having, and why.
Frozen transfers are also associated with babies at the larger end of the range, where fresh transfers lean small. The absolute difference is modest. Beyond that the risks belong to the pregnancy, not the transfer. Ectopic pregnancy stays slightly more common after IVF of any kind. A twin pregnancy from two embryos is riskier for the babies and for the person carrying them.
Frozen transfer results
Live birth rates after a frozen transfer track the age of the egg at collection, not your age at transfer. Broadly, registry figures put the rate per frozen transfer at roughly a quarter to a third where the eggs were collected before thirty-five. It falls through the late thirties, and into low single figures where the eggs came from the mid forties. An embryo frozen at thirty-two does not age in storage.
For most people a frozen transfer does at least as well as a fresh one. For high responders it does better, because the uterus is not being asked to accept an embryo while the ovaries are still swollen. That comparison is where the freeze-all habit came from. Medicated and natural cycles look broadly similar on live birth rates in the trials so far, which is why the argument has moved to what happens later in the pregnancy.
The number worth asking for is how many live births a clinic gets per egg collection, counting every transfer from the batch. It matches how treatment actually runs, and it is the most useful figure a clinic can give you. If a batch runs out without a baby, that is not a sign anything was done badly, and your clinic will use what it learned to plan the next step.
Alternatives to frozen transfer
The alternative is a fresh transfer in the collection cycle. It is a real option where the ovaries responded moderately, the progesterone behaved, and you would rather not wait another month. Where the response was strong, fresh is the riskier of the two, and most clinics will say so.
The choice that actually sits in front of you is between the two frozen cycles. If you ovulate reliably, a natural cycle is worth raising, and your clinic can explain which it recommends and why. If you do not, the medicated cycle is the treatment, and the question becomes what support you get through the first trimester.
If several transfers from a good batch have not worked, the most useful conversation is about the embryos themselves, which may point to testing or to donor eggs.
IVF
Conventional IVF, where the ovaries are stimulated to produce a batch of eggs, the eggs are collected under sedation and mixed with sperm in the laboratory, and one embryo is transferred. The core treatment that the other pages in this group are variations on.
Best for: anyone whose tubes, sperm or time make natural conception unlikely, and who wants the treatment with the best odds per attempt
Combining frozen transfer with other treatment
There is no anaesthetic, so nothing gets combined with the transfer the way operations are. What gets stacked in front of it instead is investigation. A hysteroscopy to look inside the uterus, a fluid scan, the removal of a polyp. All of them are worth doing before a transfer rather than after a failed one.
Embryo testing is the other thing planned around a frozen transfer. PGT-A has to be decided before collection, and waiting for the results is a common reason a clinic freezes everything. Embryos made later from frozen eggs, or frozen as embryos in the first place, arrive at the same place. A batch in storage, waiting for a lining to be ready.
Frozen transfer cost
A quoted IVF cycle fee is the first of two numbers, and a frozen transfer is the second. It is priced on its own, and a batch of embryos may mean paying it more than once, so it is worth asking about while you are choosing a clinic.
What sits inside the fee varies. Thawing, the monitoring scans, the transfer and a pregnancy test, usually. The drugs for the lining are sometimes separate. Storage is billed annually, often by direct debit, whether or not you are treating that year.
Three things are worth asking about up front. What happens to the fee if a cycle is cancelled. The cost of moving embryos between clinics or countries. And the add-ons offered for transfers.
Endometrial receptivity testing, scratching and immune protocols are all offered at this stage, usually after a transfer has not worked. The evidence that they improve live birth rates is weak, so it is worth deciding your view on them calmly, in advance.
Ask for a written schedule that covers one collection and every transfer the embryos from it would allow, with storage. That total is the price of the treatment.
| Country | Self-pay | Public / insurance |
|---|---|---|
| United States Storage roughly $500–$1,000 a year; thaw, monitoring and lining drugs sometimes quoted separately | $4,000–$7,000 per transfer | Depends on employer and state mandate; some plans cover transfers only after a covered collection |
| United Kingdom Storage consents run in fixed periods and lapse if not renewed | £1,500–£3,000 per transfer, plus £300–£500 a year storage | NHS-funded cycles usually include frozen transfers from that cycle, but the number varies by local area |
| Europe Spain, Czechia and Greece are the usual cross-border destinations, and embryos can be shipped in | €1,200–€2,500 per transfer, plus storage | Often included where a state system funds the collection cycle; rules differ sharply by country |
| Thailand Storage priced per year; a transfer means a return trip of roughly two to three weeks | $1,500–$3,500 per transfer | Self-pay only for international patients |
Read more: IVF
Choosing a clinic for frozen transfer
A frozen transfer is a laboratory job with a ten-minute appointment attached. The embryologists who froze and thawed the embryo matter more than whoever holds the catheter. So ask two things of the laboratory. What proportion of its embryos survive the thaw, and how many live births it gets per egg collection across every transfer from a batch.
Then ask which cycle they default to, and what would make them choose the other. Most clinics have a settled preference. The best ones say so plainly, give you the reasoning, and tailor it to your cycles.
Two more. How many embryos they transfer as standard, because anything other than one needs a specific reason. And what they would do differently on a second transfer from the same batch. A considered answer means they treat the batch as a course of treatment, which is what it is.
At the consultation
Ask what happens if the embryo does not survive the thaw. Whether they call you before or after you have set off, whether the fee is refunded, and whether another embryo is thawed the same day. It is an unlikely morning that becomes much easier when you already know the answer.
Clinics that do frozen transfer
Frequently asked questions
Is a frozen transfer as good as a fresh one?
For most people it is at least as good, and for high responders it is safer. See results for the figures and what they depend on.
Medicated or natural cycle — which should I have?
Whichever your own cycles allow, and it is worth asking rather than assuming. See how it's done for what each involves and risks for the open question about medicated cycles.
Can an embryo be damaged by freezing?
Not by the freezing itself, with modern vitrification. Storage time does not appear to matter either; an embryo frozen five years ago behaves like one frozen last month.
Do I need time off work?
No. Most people are back at their desk the same afternoon. See afterwards for what the progesterone feels like.
How long can embryos stay in storage?
Years, subject to your country's legal limit and your consents staying in date. Keep the expiry date in your own calendar as well as the clinic's, so renewal is never missed.