Both modality of embryo transfer has its own merits and demerits. frozen embryo transfer (FET) and fresh embryo transfer depends on individual patient factors, hormonal condition, uterine status, etc. lets discuss their pros and cons:
1. Success Rates
FET :
- In patients with PCOS, high ovarian reserve, or elevated progesterone during stimulation Frozen embryo transfer is associated with better implantation rate and pregnancy rate because of controlled hormonal condition.
- Also chances of ovarian stimulation decreases to large extend with this method in such cases.
Fresh Transfer:
- It can be good option in young healthy patient with low risk of OHSS.
- In patients with PCOS, high ovarian reserve, or elevated progesterone during stimulation Fresh embryo transfer is associated with poor implantation rate and pregnancy rate.
2. Hormonal Environment
FET:
- In frozen embryo transfer, we prepare endometrium to get ready for pregnancy with medicine or we wait for endometrium to get ready by monitoring the natural cycle. So frozen embryo transfer is well controlled and monitored cycle. After confirming endometrium status, ovarian status and hormonal status, we go for transferring embryo. Because of this chances of implantation increases.
Fresh Transfer:
- Transfer occurs in the same cycle as ovarian stimulation, which may disrupt natural endometrial development and chances of pregnancy may decrease. So its preferred in very few cases.
3. OHSS (Ovarian Hyperstimulation Syndrome) Risk
FET:
- No risk of OHSS, as transfer happens after recovery from stimulation.
Fresh Transfer:
- Increased OHSS risk, especially in high responders.
4. Embryo Quality & Selection
FET:
- Frozen embryo allow us to do genetic testing on embryo. Whenever result of embryo is available then we can transfer genetically normal embryo into uterus. Thereby increasing chances of healthy pregnancy.
Fresh Transfer:
- As of now, As genetic testing report takes some time, it is not possible to do genetic testing report on blastocyst stage embryo and transfer it on same day.
5. Convenience & Planning
FET:
- More flexible; transfer can be scheduled and optimized for uterine receptivity.
Fresh Transfer:
- Requires immediate coordination after egg retrieval and embryo development.
6. Cost Consideration
FET:
- Involves additional cost for freezing, storage, and thawing.
Fresh Transfer:
- May be less expensive in a single cycle setting.
When FET is Preferred
- PCOS or high responders (risk of OHSS)
- Elevated progesterone in stimulation cycle
- Need for PGT or embryo banking
- Thin or non-ideal endometrium in the fresh cycle
- Surrogacy or donor cycles
When Fresh Transfer is Suitable
- Young women with good ovarian response
- Low risk of OHSS
- No elevated progesterone levels
- Good endometrial thickness and timing
Conclusion
Frozen embryo transfer has advantage of better chances of implantation and pregnancy, specially in cases like PCOS, Elevated progesterone level in stimulation cycle, need for genetic testing of embryo, non ideal endometrium thickness. Consult with your nearest Fertility Specialist now.
