Frozen Embryo Transfer (FET) for Surrogacy: Everything You Need to Know

Once intended parents begin their surrogacy process, they will have to decide between a fresh or frozen embryo transfer (FET). There are a lot of people who want to understand what frozen embryo transfer is and how it functions in a gestational surrogacy. 

This guide will explain the FET process and will show you the frozen embryo transfer timeline. It includes success rates and costs in the US and Canada. After the procedure of frozen embryo transfer, you will know what you can expect and what you can do to encourage a successful result.

Key takeaways

• FET transfers a previously frozen, thawed embryo into the surrogate’s prepared uterus, today’s most common method in gestational surrogacy.
• A typical cycle runs 4–8 weeks from baseline to pregnancy test.
• With modern vitrification, >95% of embryos survive thawing and success rates match or beat fresh transfer.
• Per-transfer live birth rates vary by age and egg source (see the data table below); donor-egg FET is roughly 50–60%.
• Single embryo transfer (SET) is the current standard to avoid twin-pregnancy risk. 

What Is a Frozen Embryo Transfer (FET)?

Frozen embryo transfer is an IVF treatment in which embryos produced in a previous egg collection cycle are transferred. These embryos are frozen and stored until they are ready to be used. The embryo is thoroughly thawed before transfer to be placed in the surrogate’s uterus. Today, frozen embryo transfer is the most popular transfer technique in gestational surrogacy.

The embryo can be sourced from the intended mother’s eggs, donor eggs, or previously frozen embryos. An embryo is inserted into the prepared uterus of the surrogate mother on the day of transfer using a thin catheter. It is fast and generally painless and takes place as an outpatient procedure. The time for a frozen embryo transfer appointment is usually less than 30 minutes.

How long does a frozen embryo transfer take?  The transfer appointment takes less than 30 minutes; the procedure itself is 10–30 minutes.

Is frozen embryo transfer painful?  The procedure is not painful for most women. A thin catheter is passed through the cervix without anaesthesia and patients go home the same day.

Fresh vs Frozen Embryo Transfer: Which Is Better in Surrogacy?

For most surrogacy programs today, frozen embryo transfer (FET) is the preferred option. It offers equal or better success rates than fresh transfer, greater scheduling flexibility, and allows genetic testing before transfer.

In recent years, there have been advancements made in the field of vitrification (a rapid-freeze technique that gives embryos >95% survival through thawing).

It has resulted in the frozen embryo transfer success rate being comparable to or better than fresh donor transfer in many instances.

Key Comparison: Fresh vs Frozen Embryo Transfer

Factor	Fresh Transfer	Frozen Transfer (FET)
Timing flexibility	Must transfer 3–5 days after retrieval	Transfer scheduled at optimal time
Cycle coordination	Donor & surrogate cycles must sync	No cycle synchronization needed
Genetic testing (PGT)	Not possible	PGT-A/PGD can be performed first
Embryo survival	N/A	>95% survival with vitrification
Stress level	Higher — multiple variables at once	Lower — embryos already exist
Success rates	Similar (historically higher)	Equal or higher with modern techniques
Cost efficiency	One cycle per attempt	Multiple transfers from one retrieval

The rate of success for surrogacy in the United States and Canada can be extremely high with a frozen embryo transfer. If the donor egg and the surrogate are both healthy, the success rate is usually between 50% and 60% per transfer. Over the years, the success rate for embryo freezing and thawing has been considerably enhanced.

The Frozen Embryo Transfer Process: Step by Step

A standard FET cycle follows seven steps, from baseline monitoring to the pregnancy test, and typically takes 4–8 weeks. 

1. Baseline Evaluation and Screening

The first step is to have a baseline monitoring appointment. This visit is typically done on days 2-5 of the surrogate’s cycle. Hormone levels like estrogen, progesterone, and LH are measured in blood tests. A transvaginal ultrasound, which is an ultrasound of the uterus, is used to assess the uterus lining. It is when the clinic can perform infectious disease screening, medical updates, and consent forms as well.

2. Uterine Lining Preparation

Next, the surrogate undergoes preparation of the uterine lining for implantation of the embryo. Most surrogates are put on estrogen for between 10 and 14 days. It can be through tablets, patches, or even injections. Monitoring appointments are done to monitor how the uterine lining grows. Clinics usually ensure that the lining is thick enough, about 7–8 mm or more.

3. Starting Progesterone

If the uterine lining is ready, then treatment with progesterone is started. Progesterone can be used in injection form, suppository form, or as a vaginal gel. This hormone renders the uterus receptive to the implanting embryo. The embryo transfer is typically done five days after progesterone is initiated (Day 5).

4. Embryo Thawing and Quality Assessment

The embryology team thaws the frozen embryo on the day of transfer. An examination of the embryo is made to ensure its survival through the thawing process.

Today’s vitrification processes can achieve a higher than 95% success rate for embryos to survive the freezing process. Embryo grade is also checked before the transfer.

5. The Embryo Transfer Procedure

A frozen embryo transfer procedure typically takes 10 to 30 minutes. A surrogate is placed on an examination table, and an ultrasound is used. A thin and flexible catheter is passed through the cervix into the uterus. The embryo is then carefully inserted into the uterus. The procedure is not painful for most women. Once the surrogate has recovered, she can go home.

6. Post-Transfer Medications

Once the transfer is done, treatment with progesterone will be continued. Most clinics will also continue with the use of estrogen. These hormones assist in the process of embryo implantation. If pregnancy is achieved, hormone treatment may continue for up to 8-12 weeks post-fertilization.

7. Pregnancy Testing After Frozen Embryo Transfer

The blood pregnancy test should be conducted 10 to 14 days after the embryo transfer procedure. This test is conducted to find out the level of hCG in the body, which is a more precise test compared to the home pregnancy test kit.

In case there is a positive pregnancy, then another blood pregnancy test is conducted two days later. Doctors compare both tests for the normal growth and development of the pregnancy.

Frozen Embryo Transfer Timeline: What to Expect Week by Week

The average schedule for a frozen embryo transfer timeline for a surrogate mother ranges between 4 and 8 weeks, from the beginning of the cycle to the pregnancy test. The following is a general timeline:

Phase / Week	Key Activity	What’s Happening
Days 1–5 of cycle	Baseline monitoring	Bloodwork + ultrasound baseline
Days 2–14	Estrogen priming	Lining grows to 7–8mm+
~Day 14–16	Lining check + progesterone start	Progesterone begins; transfer date set
~Day 19–21 (P+5)	Transfer Day	Embryo thawed, transferred to uterus
Days 1–5 post-transfer	Implantation window	Embryo travels to uterine wall
Days 5–9 post-transfer	Implantation attempt	Embryo begins to implant
Day 10–14 post-transfer	Beta-hCG blood test	Pregnancy confirmed or not
Weeks 6–8 (if pregnant)	First ultrasound	Heartbeat detected; OB care begins

Note: The timeline above is just a general overview. Your reproductive endocrinologist and surrogacy program coordinator will develop an individualized frozen embryo transfer calendar for your particular cycle. 

Frozen Embryo Transfer Success Rates: What the Data Says

According to 2023 CDC/SART data (cited in Sources), FET live birth rates per transfer are:

Success Rates by Age (Per Transfer)

• Under 35 years: 40%-50% live birth rate per transfer; blastocyst transfers can have higher success rates
• 35-37 years: Approximately 38%-42% per transfer
• 38-40 years: Approximately 28%-35% per transfer
• Over 40 years (own eggs): Approximately 15%-20% per transfer
• Egg donor FET (all ages): 50%-60% per transfer

5-Day Frozen Embryo Transfer Success Rates

In most cases, surrogacy FET treatments involve day 5 blastocysts. Blastocysts become available five to six days after the fertilization process. Among all embryo stages, the success rate is highest with 5-day frozen embryo transfer.

Day-6 blastocysts also demonstrate good results. According to research, the clinical pregnancy rate is approximately 54.2% for Day-6 embryos (Zong et al., 2023). Due to such high success rates, day 5 and day 6 blastocysts are highly popular in surrogacy programs.

1 Frozen Embryo Transfer vs 2 Frozen Embryo Transfer Success Rates

A key question intended parents face is whether to transfer one or two embryos. The current standards suggest that single embryo transfer should be performed during surrogacy:

• 1 frozen embryo transfer success rate: The success rate for chromosomally normal (euploid) blastocysts typically ranges from 50% to 65% per cycle.
• 2 frozen embryo transfer success rate: comes a bit higher – about 65%-70% per cycle.

However, transferring two embryos entails higher risks of twin pregnancy. Besides, it increases the possibility of premature birth.

That is why most infertility experts in both the United States and Canada advise their patients to consider SET as a better alternative.

Cumulative Success Rates

The chances of success increase when multiple frozen embryo transfer cycles are available from a single egg retrieval. With three euploid embryos, the cumulative live birth rate can exceed 85% to 90%. It is one reason why creating multiple embryos during one IVF cycle can be cost-effective over time.

How to Prepare for Frozen Embryo Transfer: Surrogate Tips

If you’re preparing yourself for your FET cycle, then read this helpful guide on how to prepare for frozen embryo transfer:

2–4 Weeks Before Transfer

Take all prescribed medications on schedule — estrogen and progesterone are time-sensitive

Attend all monitoring appointments — through blood tests and ultrasounds, you’ll know that your lining is ready.

Eat a nutrient-dense diet – leafy vegetables, lean proteins, healthy fats, and whole grains.

Stay hydrated — you should drink no less than 8 glasses a day

Exercise, but only light forms – such as walking or yoga

Abstain from alcohol and smoking

When to Stop Drinking Before Frozen Embryo Transfer

Stop drinking alcohol for at least three months before the transfer This is believed to increase uterine lining health. As a minimum, people should cease consuming alcohol after starting medication for FET. Therefore, most fertility experts recommend staying off all alcohol during the entire FET period.

What to Do After Frozen Embryo Transfer

After the transfer, follow your clinic’s medication schedule and rest normally. Complete bed rest is not recommended. The two-week wait (TWW) until the pregnancy test can be emotionally intense; here is what to do:

The First 24–48 Hours

• Rest, but do not take complete bed rest, as it is not scientifically proven that one needs complete bed rest after embryo transfer.
• Take progesterone and estrogen supplements exactly as recommended by the doctor and don’t miss any dose.
• Keep yourself warm and comfortable, as exposure to temperature variations like sauna baths is harmful.
• Maintain healthy eating habits and drink plenty of water.

Days 3–14: The Two-Week Wait

• Stay away from lifting heavy objects and exercising intensely until after your pregnancy test.
• Do not do a pregnancy test at home before Day 10. The use of progesterone drugs may give a wrong diagnosis, whereas taking the test early could be stressful.
• Learn to handle stress effectively through such practices as meditation, walking, writing a journal, and receiving surrogate care. 
• Watch out for strange symptoms. Spotting due to implantation occurs in most women. However, excessive bleeding, cramping, or fever requires professional evaluation.
• Participate in your blood tests on days 6 to 7.

When to Test

An official pregnancy test is performed after frozen embryo transfer via a blood beta-hCG (pregnancy hormone) test at the clinic on Day 10-14. In case the result is positive, another blood beta-hCG test 2 days after will confirm doubling. Ultrasound to detect a heartbeat is usually arranged between 6 and 7 weeks of gestation. 

Final Thoughts

A frozen embryo transfer is more than just a medical procedure. It symbolizes the time when the dream of parenthood and the blessing of surrogacy intersect. Frozen embryo transfer comes with various benefits for intended parents in both the United States and Canada.

FET is also less stressful than fresh transfer because the embryos already exist before the surrogate’s cycle begins. Common next questions from intended parents include the cost of FET, the preparation protocol, and what to expect after the transfer.

Regardless of which stage you are at, one thing you must do is hire a reproductive endocrinologist and a surrogacy specialist. This will help make things easier for you. We help connect intended parents and surrogates in both the United States and Canada.

Most Commonly Asked Questions (FAQ)? 

Sources

• Society for Assisted Reproductive Technology (SART) — SART National Summary Report: IVF and FET Success Rates. SART, 2023.
• Shi, Y., et al. — “Transfer of Fresh versus Frozen Embryos in Ovulatory Women.” New England Journal of Medicine, 2018.
• Chen, Z. J., et al. — “Fresh versus Frozen Embryos for Infertility in the Polycystic Ovary Syndrome.” New England Journal of Medicine, 2016.
• Zong, L., et al. — “Finding of the optimal preparation and timing of endometrium in frozen-thawed embryo transfer: a literature review.” Frontiers in Endocrinology, 2023. PubMed: PMC10497870.