FET vs Fresh Transfer: Key Differences
Whether you had a fresh or frozen embryo transfer, your due date is calculated the same way. Here is a complete comparison of the two approaches and what they mean for your pregnancy.
FET
Frozen Embryo Transfer. Embryos are cryopreserved after retrieval and transferred in a later, separate cycle with the uterine lining prepared specifically for implantation.
Fresh Transfer
Embryo transfer occurs in the same cycle as egg retrieval, 3–6 days after fertilization. The body is still recovering from ovarian stimulation.
Side-by-Side Comparison
| Aspect | 🧊 FET | 🥚 Fresh Transfer |
|---|---|---|
| Timing | Transfer in a separate, future cycle (weeks to months later) | Transfer occurs 3–6 days after egg retrieval, in same cycle |
| Uterine environment | Lining prepared specifically for implantation — potentially better | High estrogen/progesterone from stimulation — may not be ideal |
| Embryo development | Typically Day 5 or Day 6 blastocysts (better selection) | Day 3 (cleavage) or Day 5 (blastocyst) |
| OHSS risk | Lower — no fresh cycle hormonal spikes | Higher risk if stimulation was aggressive |
| Success rates | Equal or slightly higher in recent registry data | Comparable; slightly lower in some studies |
| PGT testing | Natural fit — biopsy, test, transfer in next cycle | Not compatible without biopsy + refreeze |
| Due date calculation | Same formula — Transfer Date + (266 − embryo days) | Transfer Date + (266 − embryo days) |
| Pregnancy management | Identical to fresh after positive test | Identical to FET after positive test |
Due Date Calculation: Same Formula
Whether your embryo was fresh or frozen, the due date formula is identical — it depends only on the embryo’s age (in days) at the time of transfer:
Day 5 transfer: EDD = Transfer Date + 261 days
Day 3 transfer: EDD = Transfer Date + 263 days
Day 6 transfer: EDD = Transfer Date + 260 days
The freezing and thawing process does not add to embryo age — only the culture days in the lab count.
Which Is Right for You?
The decision between fresh and frozen transfer is made by you and your reproductive endocrinologist based on your individual medical circumstances, hormone levels at retrieval, embryo quality, and clinic protocols. Both approaches are well-established, safe, and have helped millions of families conceive.
Once a transfer is successful and pregnancy is confirmed, the management of an IVF pregnancy — and the path to your due date — is the same regardless of whether it was a fresh or frozen transfer.
Frequently Asked Questions
Common questions answered by our medical team