Frozen Embryo Transfer (FET): What to Know Before Your Cycle

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If you have been through an IVF cycle and have frozen embryos waiting, or if your doctor has recommended a frozen embryo transfer (FET) rather than a fresh transfer, you may be wondering exactly what this involves and why. This article explains FET clearly — from preparation to the transfer itself to what to expect in the days that follow.

What Is a Frozen Embryo Transfer?

A frozen embryo transfer is exactly what it sounds like: embryos that were created during a previous IVF cycle, frozen using a technique called vitrification (ultra-rapid freezing), are thawed and transferred to the uterus. The embryos can be stored for many years and retain their quality remarkably well after thawing.

Why Choose FET Over a Fresh Transfer?

There are several good reasons why a FET cycle may be recommended or preferred over a fresh embryo transfer:

Risk of OHSS

If your ovaries responded strongly to stimulation during egg collection — a situation more common in women with PCOS — your doctor may recommend freezing all embryos and doing a FET in a subsequent, natural cycle. This avoids the risk of ovarian hyperstimulation syndrome (OHSS) being worsened by pregnancy hormones.

Genetic Testing (PGT-A)

If your embryos underwent pre-implantation genetic testing, the results take time to return. Your embryos must be frozen while you wait. Only chromosomally normal embryos are then transferred in a FET cycle.

Uterine Concerns

If a polyp, fibroid, or uterine lining issue was identified after egg collection, it is safer to freeze and address the concern before transfer.

Better Outcomes

Research increasingly shows that FET cycles may have higher success rates than fresh transfers in many patient groups. This is thought to be because the uterus has had time to recover from the stimulation medications, and the endometrium (uterine lining) is in a more natural, receptive state.

How Is the Uterus Prepared for FET?

There are two main protocols for preparing the uterine lining:

Natural Cycle FET

We monitor your natural cycle with ultrasound and hormone blood tests to detect ovulation. Transfer is timed to occur when your uterine lining has developed naturally under your own hormones. This approach is gentle and avoids medication.

Medicated (Artificial) Cycle FET

Oestrogen tablets or patches are taken for 10–14 days to thicken the uterine lining, followed by progesterone pessaries or injections to mimic the secretory phase of the natural cycle. Transfer is scheduled for a precise point after progesterone begins. This approach gives us more control over timing and is the most commonly used protocol.

The Transfer Day

On the day of transfer, our embryologist thaws your chosen embryo and checks its viability under the microscope. A high percentage of frozen embryos survive the thawing process — our vitrification protocol achieves excellent survival rates. The transfer itself is identical to a fresh transfer — a thin catheter is passed through the cervix and the embryo is gently placed into the uterus under ultrasound guidance. It is painless and takes about 10 minutes.

After the Transfer — The Two-Week Wait

Progesterone support continues after transfer for approximately 10–12 weeks if pregnancy is confirmed. You will take a blood pregnancy test (beta hCG) approximately 10–14 days after transfer. During this time, continue your normal activities, rest when you feel you need to, and be kind to yourself.

Frequently Asked Questions

Can frozen embryos be kept indefinitely?

Embryos can be stored safely for many years. In India, the legal limit for storage is typically 5 years, with the possibility of extension in certain circumstances. We will advise you on storage arrangements.

What if the embryo does not survive thawing?

In a small percentage of cases, an embryo may not survive the thaw. If this happens, we would discuss your remaining embryos and next steps. Our vitrification protocol achieves very high survival rates, so this is uncommon.