If you are preparing for a frozen embryo transfer as a surrogate, you may be wondering, on which day of cycle is frozen embryo transfer done? This question is important, and the answer depends on several factors including your cycle, the protocol chosen by your fertility specialist, and the stage of the frozen embryo being transferred. Whether you are in a medicated cycle or a natural cycle FET, timing is everything when it comes to achieving successful implantation and ultimately a successful pregnancy.
At Made in the USA Surrogacy, we know how important it is for surrogates to feel informed and supported through every phase of their journey. This detailed guide explains exactly when in your menstrual cycle a frozen embryo transfer usually occurs, how the timing is determined, and what factors can affect the frozen embryo transfer timeline.
Understanding Frozen Embryo Transfer
A frozen embryo transfer, or frozen embryo transfer FET, is part of the broader in vitro fertilization process. After an embryo is created in a lab using IVF treatments, it may be frozen for later use. Many surrogates participate in a transfer using an embryo that was created in a previous IVF cycle.
Frozen embryo transfer is different from a fresh embryo transfer, where the embryo is transferred in the same cycle as egg retrieval. In a FET cycle, the embryo is thawed after being cryopreserved, then transferred at the optimal stage of the surrogate’s cycle. The embryo transfer process is timed very precisely to ensure that the uterus is ready to receive the embryo for successful implantation and support prenatal development.
Genetic testing is often performed on embryos before freezing to select healthy embryos with the best chance of implantation and healthy prenatal development. Not all embryos survive the thawing process, so remaining embryos may be preserved for multiple attempts if the first transfer is unsuccessful.
The Role of the Menstrual Cycle in Embryo Transfer Timing
The menstrual cycle plays a key role in preparing a woman’s uterus for embryo implantation. The cycle includes several stages: menstruation, the follicular phase, ovulation, and the luteal phase. The uterus lining thickens naturally in preparation for a potential pregnancy during the luteal phase, and the embryo is transferred at the point when the uterine lining is most receptive.
In a natural cycle FET, your fertility specialist, often a reproductive endocrinologist, monitors your body’s natural processes to detect ovulation. Once confirmed, the frozen embryo transfer is scheduled based on the embryo’s age and when it would normally arrive in the uterus.
In medicated cycles, hormones are administered to mimic your body’s natural hormonal stimulation and luteal phase support. These medications help control the frozen embryo transfer timeline and create a predictable environment for the embryo. Many female hormones, including estrogen and progesterone, play essential roles in preparing the uterine environment and supporting reproductive health.
IVF Frozen Embryo Transfer in Medicated Cycles
Most surrogates undergo a medicated cycle for their FET. This method provides complete control over the timing of the transfer and helps ensure that the endometrial lining is at the optimal thickness. Here’s how a typical medicated IVF frozen embryo transfer works:
Cycle Days 2 to 3
The process begins with baseline monitoring on cycle day 2 or 3. Blood tests and ultrasounds are used to ensure the reproductive system is ready for hormone treatment. At this stage, your fertility doctor will evaluate your reproductive organs and confirm that your body is ready for hormonal preparation, including ovarian stimulation if needed.
Estrogen Support Begins
After a successful baseline, estrogen medication is started. Estrogen helps thicken the uterus lining or endometrial lining to a level that is ideal for implantation. This part of the IVF cycle usually lasts about 10 to 14 days. The fertility clinic will schedule multiple appointments to check the uterine environment and ensure proper development of the endometrial lining.
Monitoring and Ultrasound
Around cycle day 12 to 14, an ultrasound is performed to check the thickness of the uterine lining. A minimum thickness of 7 to 8 mm is often considered ideal, although your fertility specialist’s recommendations may vary. If the lining meets the necessary criteria, progesterone is added to the medication regimen.
Progesterone and Embryo Transfer Timing
The day progesterone begins is crucial because it marks the start of the luteal phase in your FET cycle. Embryo transfer is scheduled based on how many days of progesterone are needed to match the developmental stage of the embryo:
- Day-3 Embryo: Transferred 3 days after progesterone begins
- Day-5 Embryo (Blastocyst): Transferred 5 days after progesterone begins
For example, if you start progesterone on cycle day 14, a Day-5 embryo would be transferred on cycle day 19. This means frozen embryo transfer often takes place between cycle days 17 and 22 in a medicated cycle.
Natural Cycle FET and Modified Natural Cycles
In some cases, surrogates may undergo a natural cycle FET, especially if they have regular cycles and predictable ovulation. A natural cycle relies on the body’s natural ovulation to time the transfer.
Natural Cycle Steps:
- Monitoring begins around cycle day 10 to detect the luteinizing hormone (LH) surge.
- Ovulation is confirmed using blood tests and ultrasound.
- Progesterone may be added post-ovulation to support the luteal phase.
- Embryo transfer is scheduled approximately 5 days after ovulation if transferring a Day-5 embryo.
Natural FET protocols require more monitoring and flexibility. However, they use fewer medications, which some surrogates prefer.
Factors That Affect Embryo Transfer Timing
Timing a frozen embryo transfer requires consideration of many factors. Your fertility specialist will carefully review:
- Embryo stage: The embryo quality and developmental day determine how many days of progesterone are needed before the embryo transfer.
- Endometrial response: Your uterus lining must be at the right thickness to support successful implantation.
- Hormonal response: Female hormones like estrogen and progesterone must reach ideal levels.
- Previous IVF cycle outcomes: Your past response to medications or embryo transfers may affect this cycle’s protocol.
- Medical team availability: Your transfer day may also depend on when the clinic is available to thaw the embryo and perform the procedure.
- Reproductive health factors: Conditions affecting the uterus or hormonal balance can influence timing and success.
The Embryo Transfer Process
On transfer day, your fertility clinic will carefully thaw the frozen embryo using a specific thawing process. Thawed embryos are checked for viability and embryo quality. Not all embryos survive thawing, but most healthy embryos have a high survival rate.
The embryo is loaded into a thin catheter and guided through the cervix into the uterus. This part of the embryo transfer process is usually quick and painless, requiring no anesthesia. The entire appointment may take under an hour, though you will be advised to rest briefly afterward.
It is important to avoid activities that may trigger uterine contractions after the transfer, as these could disrupt implantation. Your fertility specialist will provide detailed post transfer care instructions.
After the Transfer: Post Transfer Care and Testing
Once the embryo is transferred, your body takes over the rest of the work. You’ll continue progesterone and estrogen support as prescribed, helping maintain a healthy uterine environment for the embryo.
Pregnancy Testing and Confirmation
About 9 to 11 days after your transfer, a pregnancy test will be scheduled. This will be a blood test to detect human chorionic gonadotropin (hCG), the hormone produced by a developing embryo.
This phase of the FET cycle is often the most emotionally intense. It’s important to follow your clinic’s instructions, avoid early at-home tests, and maintain a calm, supportive environment.
Tips for Supporting Successful Implantation
While your clinic handles the medical side, there are a few things surrogates can do to support a successful transfer and overall reproductive health:
- Follow your medication schedule exactly
- Eat a balanced diet including seeds, lean proteins, healthy fats like extra virgin olive oil, and low mercury fish
- Stay hydrated and avoid extreme temperatures
- Opt for warmer foods to support circulation and uterine lining health
- Rest as instructed by your medical team
Frequently Asked On Which Day of Cycle Is Frozen Embryo Transfer Done Questions
On which day of cycle is frozen embryo transfer done?
In a medicated FET cycle, embryo transfer usually takes place between cycle days 17 and 22, depending on when progesterone begins and the developmental stage of the embryo.
Can the embryo transfer day change during the cycle?
Yes, if your uterine lining or hormone levels aren’t ideal, your fertility specialist may adjust the frozen embryo transfer timeline. Flexibility is key to achieving the best results.
What if I’ve had a previous IVF cycle?
Having a previous IVF cycle allows the clinic to use stored embryos for your FET. Your response to previous cycles may help the fertility specialist fine-tune your current protocol.
How long is the full FET cycle from start to finish?
From the first monitoring appointment to the embryo transfer, a medicated FET cycle usually lasts about 3 to 4 weeks.
What are the success rates for frozen embryo transfer?
Success rates vary based on embryo quality, woman’s age, fertility clinic experience, and the surrogate’s uterine environment. Many clinics report success rates between 50 and 70 percent for single embryo transfers using frozen embryos.
Final Thoughts
Frozen embryo transfer is a precise and medically guided process that plays a critical role in every surrogacy journey. As a surrogate, understanding your menstrual cycle, the medications involved, and the frozen embryo transfer timeline will help you feel confident and empowered.
The answer to on which day of cycle is frozen embryo transfer done may vary, but with the right medical team and fertility specialist guiding your FET cycle, you can trust that everything is aligned for the best possible outcome. Your role in carrying a healthy pregnancy for someone else is nothing short of remarkable.
If you are considering surrogacy or are in the early stages of your fertility journey, our team at Made in the USA Surrogacy is here to help you every step of the way. Contact us today to learn more about becoming a surrogate and starting your journey toward a successful transfer.
