One of the most common decisions in IVF is whether to proceed with a fresh embryo transfer or to freeze all embryos and transfer one in a subsequent cycle. Both approaches have advantages, and the best choice depends on your individual medical situation. Here is what you need to know about each option.
What Is a Fresh Embryo Transfer?
In a fresh transfer cycle, embryos are transferred to the uterus within the same cycle as egg retrieval. After your eggs are collected and fertilised in the laboratory, the resulting embryos are cultured for either 3 days (cleavage stage) or 5 days (blastocyst stage) before one is selected and transferred.
The main advantage of a fresh transfer is that the entire IVF process — from stimulation through transfer — is completed in a single cycle, which can feel like a faster path to pregnancy. However, your body has just gone through hormonal stimulation and egg retrieval, which means the uterine environment may not be in its most receptive state.
What Is a Frozen Embryo Transfer (FET)?
In a frozen embryo transfer cycle, all viable embryos from the retrieval are cryopreserved (frozen) using a rapid-freezing technique called vitrification. The transfer is then scheduled in a later cycle — typically 1–2 months after retrieval — giving your body time to recover.
FET cycles involve less medication and are less physically demanding. Your lining is prepared either with a natural cycle (monitoring your own ovulation) or a medicated cycle (using oestrogen and progesterone), and the embryo is thawed and transferred at the optimal time.
Comparing Fresh and Frozen Transfers
| Aspect | Fresh Transfer | Frozen Transfer |
|---|---|---|
| Timeline | Same cycle as retrieval | 1–2+ months later |
| Body recovery | Still recovering from stimulation | Fully recovered |
| Uterine lining | May be affected by hormones | Naturally or optimally prepared |
| OHSS risk | Higher if high response | Eliminated by freeze-all |
| Medications needed | Continuous from stimulation | Oestrogen + progesterone only |
| PGT-A possible? | Sometimes (Day 5 biopsy) | Yes — standard approach |
Success Rates: Is One Better Than the Other?
For many years, fresh transfers were the standard. However, improvements in vitrification technology have made frozen transfers increasingly successful. Current research suggests that frozen transfers may produce comparable or slightly better outcomes for many patients, particularly:
- Women at risk of ovarian hyperstimulation syndrome (OHSS)
- Patients undergoing preimplantation genetic testing (PGT-A)
- Women with elevated progesterone at trigger
- High responders with many eggs retrieved
That said, fresh transfers remain a perfectly valid option for many patients, particularly those with normal responses and optimal lining thickness. Your fertility specialist will recommend the approach best suited to your specific situation.
How Does Transfer Type Affect Your Due Date?
Key Fact
Whether your embryo was transferred fresh or frozen does not change your due date calculation. The formula depends only on the date of transfer and the embryo stage (Day 3 or Day 5). The freezing and thawing process does not alter the embryo’s developmental age.
The Vitrification Process: How Safe Is Freezing?
Modern embryo freezing uses vitrification, an ultra-rapid freezing technique that cools cells so quickly that ice crystals — which can damage delicate cell structures — cannot form. Vitrification has revolutionised IVF outcomes:
- Survival rates after thawing exceed 95–99% for blastocysts
- No known increase in birth defects compared to fresh transfers
- Embryos can be stored indefinitely without degradation
What to Expect on Transfer Day
Regardless of whether you are having a fresh or frozen transfer, the actual transfer procedure is the same. It is a brief, usually painless procedure that takes about 5–10 minutes and does not require anaesthesia.
You will be asked to arrive with a comfortably full bladder (this helps with ultrasound visibility). Using ultrasound guidance, your doctor will pass a thin catheter through the cervix and deposit the embryo into the uterine cavity. Afterwards, you will rest for a short period before going home.
Most clinics recommend light activity for the rest of the day, but strict bed rest is no longer considered necessary or beneficial.