In short: In IVF, an embryo can be placed in the womb either during the same month your eggs are collected (fresh transfer) or after being frozen and thawed in a later month (frozen embryo transfer, or FET). This article answers one question: Is a fresh or a frozen embryo transfer the better choice for you?

What is the difference between fresh and frozen transfer?

The goal of both methods is the same: to place a healthy embryo into the womb at the right moment. The difference is when the transfer happens.

• Fresh transfer: The embryo is transferred within the same stimulation cycle in which your eggs were collected, usually 3–5 days later.
• Frozen transfer (FET): Embryos are stored using a rapid freezing method called vitrification, then thawed and transferred in a separate cycle once your body has recovered from the stimulation medications.

In recent years, many centres have shifted increasingly toward frozen transfer. This is because freeze-thaw technology has improved dramatically and the lining of the womb (endometrium) can be prepared in a more natural environment.

Is fresh or frozen more successful?

There is no single answer that fits everyone. In appropriately selected patients, the chance of a live birth is largely similar between the two methods. What matters is which approach fits your individual picture best. With modern vitrification, the survival rate of embryos after thawing is very high, so the worry that “a frozen embryo is weaker” is not supported by today’s data. You can find our overall success framework and the full journey on our IVF treatment in Istanbul page.

Who is frozen transfer (FET) more suitable for?

In some situations, freezing the embryo and postponing to a later cycle is safer and more sensible:

• Risk of ovarian hyperstimulation (OHSS): In patients who respond strongly to medication, postponing a fresh transfer clearly reduces this risk.
• When genetic testing is planned (PGT): Because a sample is taken from the embryo and results are awaited, the embryos are frozen and the healthy one is transferred in a later cycle.
• Hormonal imbalance during stimulation: An early rise in progesterone on collection day can reduce how well the womb lining accepts the embryo; in such cases, freezing and waiting gives a better result.
• Problems with the womb lining: A thin endometrium, a polyp, or fluid in the womb that cannot be corrected in the fresh cycle may lead to postponing the transfer.
• Polycystic ovary syndrome (PCOS): In this group, frozen transfer can offer higher success and lower risk for some patients.

When is fresh transfer preferred?

Freezing is not always necessary. In patients with a measured ovarian response, a suitable hormone balance, and a womb lining that looks ideal in the fresh cycle, fresh transfer remains a very reasonable option. It can shorten the process and may avoid an extra waiting cycle. So the decision is not “which is generally better” but “what does your picture show in this cycle.”

What is the “freeze-all” strategy?

In some plans, no fresh transfer is done at all; every healthy embryo is frozen and the transfer is left to a later cycle. This is called the “freeze-all” approach. The aim is to place the embryo in a calmer, more natural hormonal environment once the body is completely free of the stimulation medications. It is preferred especially when there is a risk of OHSS, an early progesterone rise, or when genetic testing is involved.

Does freezing harm the embryo?

Vitrification lowers the embryo to a very cold temperature within seconds, preventing ice-crystal formation. As a result, the great majority of embryos come through thawing safely. Healthy babies born from frozen and stored embryos are now routine. If you would like to understand how it is done, you can read our article on embryo cryopreservation (freezing).

How is the decision made?

The answer to “fresh or frozen” is personal, and several factors are weighed together:

• Your ovarian response and OHSS risk.
• Your hormone values on collection day.
• The condition of your womb lining.
• Whether genetic testing will be performed.
• Your age and general medical history.

Age has a special place in this decision; as the strongest predictor of egg quality, it directly shapes the plan. If you would like to go deeper, our article on IVF success rates by age is a good starting point.

Appointment and contact

To clarify the fresh-versus-frozen question for your own situation and to build the plan that suits you best, you can book an appointment at our clinic at Biruni University Hospital in Istanbul. Rather than applying the same recipe to every case, we map out a route that aims for the highest chance using your own data.

This article is for information only and does not replace a personal examination and medical assessment. Treatment decisions should be made together with your doctor after evaluating your results and history.