Frozen Embryo Transfers: Is Delayed Better?
When undergoing in vitro fertilization (IVF), patients must decide whether to proceed with a fresh embryo transfer or a frozen embryo transfer (FET). While fresh transfers occur in the same cycle as egg retrieval, frozen embryo transfers involve freezing embryos for later use. In recent years, FETs have gained popularity, leading many to ask: Is delayed embryo transfer actually better?
What is a Frozen Embryo Transfer?
A frozen embryo transfer occurs when embryos are cryopreserved (frozen) after fertilization and later thawed for implantation in a future cycle. Unlike fresh transfers, FETs allow the body time to recover from ovarian stimulation and enable precise hormonal control for optimal implantation conditions.
The Benefits of Delaying Embryo Transfer
1. Improved Uterine Environment
One of the biggest advantages of a frozen transfer is the ability to optimize the uterine environment. During fresh transfers, the body is still under the influence of ovarian stimulation drugs, which can lead to high estrogen levels and a less receptive endometrium. In contrast, FET allows the uterus to return to its natural state, creating a more favorable environment for implantation.
2. Higher Pregnancy Success Rates
Studies suggest that FETs may lead to higher implantation and live birth rates compared to fresh transfers, particularly for women with high estrogen levels. Research shows that freezing embryos and transferring them in a later cycle reduces the risk of implantation failure due to hormonal imbalances.
3. Reduced Risk of Ovarian Hyperstimulation Syndrome (OHSS)
For women at risk of OHSS, a condition caused by excessive ovarian response to fertility medications, delaying transfer can be beneficial. Freezing embryos allows time for the body to recover before attempting pregnancy, making FET a safer option for high-risk patients.
4. Better Timing for Genetic Testing
Many couples opt for preimplantation genetic testing (PGT) to screen embryos for genetic abnormalities. Since PGT requires additional time for analysis, freezing embryos ensures that the transfer is not rushed, allowing doctors to select the healthiest embryo for implantation.
5. Flexibility and Convenience
FETs offer greater flexibility, as they allow patients to schedule transfers at a time that best suits their health and lifestyle. This is particularly useful for women recovering from egg retrieval, managing other health conditions, or wanting to prepare their body for pregnancy optimally.
Are There Any Downsides to Delaying?
1. Emotional and Physical Waiting Period
For some patients, waiting for an FET can be emotionally challenging, especially after going through the intense process of egg retrieval. The delay may feel frustrating for those eager to conceive quickly.
2. Embryo Survival Rates
Although modern freezing techniques like vitrification have significantly improved survival rates, there is still a small chance that an embryo may not survive the thawing process. However, the risk is low, with survival rates exceeding 95% in most clinics.
3. Additional Costs
FETs may require additional costs for embryo freezing, storage, and thawing. However, many patients find the improved success rates and reduced health risks to be worth the investment.
Conclusion: Is Delayed Transfer the Better Choice?
For many patients, frozen embryo transfer offers a safer and more effective option, particularly for those with high estrogen levels, OHSS risk, or those undergoing genetic testing. While fresh transfers may still be suitable for some, the benefits of delaying implantation—such as a healthier uterine environment and improved success rates—make FET a preferred choice for many fertility specialists. Ultimately, the decision should be made based on individual medical factors and in consultation with a fertility expert. Check out this paper so you can make your own decision!
At the IVF Kitchen, we feel a major factor in this decision ultimately comes down to your fertility doctor, and here’s why. These top fertility doctors have already found a formula or stimulation plan that works most effectively for them even though it’s not always the best route for the patient. Almost always the doctor will pick the route they’re used to and they can easily back it up with clinically relevant studies. For example, we know many patients who visited one of the top fertility clinics in New York and they only ever did fresh transfer, but a clinic we work closely with only ever recommended frozen transfer for the same patient. Both clinics are extremely successful with their patients, but many patients who require extra attention slip through the cracks and are not so lucky. We’re not here to say what is right or wrong, but it certainly helps to know more and be better informed!
“Frozen embryo transfers are like leftovers—they often turn out better after a little time to settle.”
