Fresh or frozen embryo transfer: timing, benefits and trade-offs

There is no single winner. Research comparing the two finds similar overall results for many people, but not for everyone, and the answer depends partly on what each study measured. The two paths also differ in more than timing: your risk of OHSS, whether embryos are being genetically tested, how your uterine lining is prepared, how many medicines and visits you need, and what you pay.

Your clinic knows your health and your embryos, so its advice comes first.

What fresh and frozen mean

In a fresh transfer, your embryo is placed in your uterus a few days after your egg retrieval, in the same cycle. This is usually 3 or 5 days after retrieval.

In a frozen embryo transfer (FET), your embryo is frozen first. It is thawed and transferred in a later cycle. The embryo may have been made months or even years before.

Some people have both: a fresh transfer first, with any other embryos suitable for freezing frozen for later.

Fresh vs frozen transfer at a glance

	Fresh transfer	Frozen transfer
When it happens	3 or 5 days after retrieval, same cycle	In a later cycle
How the lining is readied	Estrogen from your own follicles, plus progesterone from your clinic	Hormones (programmed) or your natural ovulation
Checks before transfer	Ultrasounds and hormone blood tests during stimulation, how you recover, and embryo updates	Ultrasounds, and in some plans blood tests, to check the lining or time ovulation
Extra medicines	Progesterone after retrieval	Programmed: estradiol, then progesterone. Natural: sometimes a trigger shot or progesterone
Genetic testing (PGT-A)	Tested embryos are usually frozen while results come back	Freezing gives time for results
Thaw step	None	Embryo is thawed; some need time in the lab first
OHSS	Pregnancy can make OHSS worse	Waiting gives OHSS time to settle
Added costs	No freezing or thaw for the embryo transferred	Freezing, storage, thawing, lining medicines and monitoring
Time to pregnancy	Likely shorter	Longer, since the transfer is delayed

How the fresh transfer calendar works

The fresh calendar is fast. During stimulation, your clinic checks your ovaries with ultrasounds and blood hormone tests. Those checks also feed the fresh-transfer decision: a rise in progesterone near the end of stimulation may lower the chance of pregnancy from a fresh transfer.

After retrieval, the lab updates you on your embryos, and your team watches how you are recovering. You will be prescribed progesterone, a hormone that supports a possible pregnancy. The transfer comes a few days later.

See the full day-by-day plan in our fresh embryo transfer guide.

How the frozen transfer calendar works

A frozen transfer has its own cycle. There are two main types.

Programmed (medicated) FET. You take the hormone estradiol to build up your uterine lining, and you have ultrasounds and blood tests to see how it responds. Some plans start with a medicine to quiet the ovaries first. When the lining is ready, you add progesterone. Its start time matters, because it sets the thaw and transfer day.

Natural FET. Your clinic follows your own ovulation. You have ultrasounds and may use ovulation kits or a trigger shot to time it. In a modified natural cycle, you also take progesterone.

Sometimes the lining takes longer to thicken than planned. That can move your transfer date and may mean extra hormones, more monitoring and more cost. Read more in our frozen embryo transfer guide.

Freeze-all: when every embryo is frozen

Some cycles skip the fresh transfer on purpose. This is called a freeze-all cycle. Reasons include:

• OHSS (ovarian hyperstimulation syndrome), when the ovaries overreact to the fertility medicines. A pregnancy can make OHSS worse or last longer, and waiting can help it settle.
• Genetic testing. Freezing gives time for PGT-A results to come back.
• A progesterone rise near the end of stimulation.
• A finding in the uterus, such as a polyp, that can affect implantation.

Learn more about the freeze-all cycle.

Is transfer day different?

Not much. In both cases, a thin, flexible tube called a catheter places the embryo in your uterus. You do not need anesthesia, and it is usually guided by an ultrasound on your belly. For a frozen transfer, the lab thaws the embryo first. Our embryo transfer day guide walks through it.

How the weeks after transfer differ

Either way, you wait for a pregnancy test on a date your clinic gives you. What can differ is how long you keep taking hormones if you are pregnant. That depends on your plan, including whether you had a fresh transfer and which type of frozen cycle you had, so your clinic sets the stop date. Keep taking your hormones until your clinic tells you to stop.

See after embryo transfer for the test and the wait.

What does the research compare?

Studies ask two different questions, and it helps to know which one you are reading about.

• One transfer: the chance of a baby from a single fresh or a single frozen transfer.
• The whole plan: freezing all embryos from a retrieval versus doing a fresh transfer first and freezing the rest. These studies count every transfer from that retrieval. The result is called the cumulative live birth rate.

These are different measures, so a result on one does not settle the other.

What does the research say?

• The whole plan: A large Cochrane review compared freeze-all with a fresh-first plan. It found probably little or no difference in the overall chance of a baby. Freeze-all may lower the risk of OHSS, while time to pregnancy is likely shorter with a fresh transfer. Freeze-all may also raise the risk of high blood pressure in pregnancy and of a larger-than-expected baby, but the authors urge caution because these findings rest on very few cases.
• People with a low chance of success: A 2025 trial at nine fertility centers in China, published in The BMJ, studied 838 women who had 9 or fewer eggs collected or a low egg supply. Live birth after the first transfer was 40% with a fresh transfer and 32% with freeze-all. Counting every transfer within one year, it was 51% and 44%. The authors say a fresh transfer may be the better choice for this group.
• People whose ovaries made many eggs: SART describes a large study in which these "high responders" had a better chance with a frozen transfer.

So no plan is best for everyone. Ask your clinic how your response to stimulation, your embryos and the reason for freezing fit these findings.

What about cost?

A frozen transfer adds steps that cost money: freezing, storage, thawing, medicines to prepare the lining, and monitoring visits. Embryos that need extra time in the lab after thawing can add more. Research on which plan costs less overall, per baby born, is limited. Ask your clinic for the full cost of each path, including storage fees.

Things to know about frozen embryos

• Not every embryo survives freezing and thawing. It is possible that none survive, which would mean no transfer that cycle.
• Before transfer day, ask how embryos like yours (same stage and freezing method) have survived warming in this lab.
• Ask what happens if the embryo does not survive: will another be warmed, who decides, and how will the clinic reach you?
• Estradiol can raise the risk of blood clots. Tell your clinic if you have ever had a clot.

Questions to ask your clinic

Bring this list to your next visit:

• Do you suggest fresh or frozen for me, and why?
• Am I at risk for OHSS?
• Will my embryos be genetically tested?
• For a frozen transfer, will my cycle be programmed or natural, and what medicines will I take?
• How many monitoring visits should I expect?
• What will each path cost in total?
• What happens if my lining is slow to thicken?
• How many embryos do you suggest transferring?

Write down the answers, or record them if your clinic is OK with it, so you can compare the two plans later.

Key takeaway

Ask your clinic which plan it suggests for you and why. Then ask how that plan changes your calendar, your medicines, your monitoring visits and your costs.