Frozen Embryo Transfer (FET): What to Expect, Step by Step
Featuring Josh Kapfhamer, MD (Center for Reproductive Medicine), Eve Feinberg, MD (Northwestern University), and Michael Baker, PhD (Aspire Fertility).
What Happens in a Frozen Embryo Transfer (FET)? A Fertility Provider Explains
Once donor embryos arrive at your clinic, the next step is a frozen embryo transfer, often shortened to FET. In the videos on this page, fertility providers walk through what a typical FET cycle looks like and the thinking behind how many embryos to transfer. Every clinic tailors the details to the individual, so treat this as a general map rather than a fixed protocol.
What is a frozen embryo transfer (FET)?
A frozen embryo transfer is a procedure in which a previously cryopreserved embryo is warmed and placed into the uterus. In embryo donation, the embryos have already been created and frozen, so the recipient’s journey centers on preparing the uterus and timing the transfer rather than on egg retrieval. The goal, as the providers explain, is a healthy single pregnancy.
Frozen embryo transfer timeline: the steps of an FET cycle
According to the providers featured, a common FET cycle unfolds in a sequence like this:
A short course of birth control pills is sometimes used first, which gives the clinic control over timing.
A baseline ultrasound checks that the uterus and ovaries are quiet and ready to begin.
Hormone preparation of the uterus begins, usually with estrogen.
A second ultrasound, roughly two weeks later, checks that the uterine lining has developed as hoped.
Progesterone is then started, and the transfer is scheduled for a set number of days afterward.
The exact medications and timing vary by clinic and by person, so your care team will give you a plan specific to you. All told, a typical frozen embryo transfer timeline runs about three to four weeks from the baseline appointment to transfer day.
What happens in the lab on transfer day
On the day of the transfer, the laboratory warms the embryo and makes an initial assessment of whether it survived the thaw, which can usually be determined fairly quickly. Closer to the transfer, some labs assess the embryo’s expansion again and may take a photo as a keepsake. As the providers note, embryos are sometimes re-graded after thawing, often simply as a record for the lab’s own quality tracking, and grades generally match from freeze to thaw. Learn more about how grading works on our embryo grading page.
How many embryos should be transferred?
How Many Embryos Should I Transfer? A Fertility Provider Explains
One of the most common questions is how many embryos to transfer at once. The providers featured explain that the goal is a healthy single pregnancy, which is generally the safest outcome for parent and baby, and that the decision is a shared one made with your clinic. Several factors inform it, including embryo quality, whether the embryos were genetically tested, and age. Transferring more than one embryo raises the chance of a twin or multiple pregnancy, which carries added risks, so a single embryo transfer is often recommended.
When embryos are stored in pairs, the providers explain that they can be warmed together, with the best one selected for transfer and the second re-frozen for a future cycle if it remains good quality. Your clinic can talk through what makes sense for your specific embryos.
Timing your transfer with donor embryos
With embryo donation, transport of the embryos to your clinic is coordinated once the legal agreement is complete. Clinics generally ask that you not schedule your transfer until that agreement is signed, because arranging transport between clinics takes time. Once the embryos are at your clinic, you can plan your transfer on a timeline that works for you.
Have questions about receiving donor embryos or planning a transfer? Contact Embryo Connections and we will be glad to help.
The videos and information on this page are educational and reflect the perspectives of the providers featured. They are not medical advice. Your own clinic will tailor your FET protocol to your situation.
Frequently Asked Questions
Q: What is a frozen embryo transfer (FET)?
A: A frozen embryo transfer is a procedure in which a previously frozen embryo is warmed and placed into the uterus. In embryo donation, the embryos are already created and frozen, so the recipient’s journey focuses on preparing the uterus and timing the transfer.
Q: What are the steps of an FET cycle?
A: A common cycle may start with a short course of birth control pills, then a baseline ultrasound, then estrogen to prepare the uterine lining, a second ultrasound to check progress, and finally progesterone, with the transfer scheduled a set number of days later. Your clinic will tailor the plan to you.
Q: How many embryos are usually transferred?
A: The goal is a healthy single pregnancy, so a single embryo transfer is often recommended. The decision is made with your clinic and considers factors like embryo quality, genetic testing, and age. Transferring more than one raises the chance of a multiple pregnancy and its added risks.
Q: Can embryos stored in pairs be transferred one at a time?
A: Yes. A pair can be warmed together, the best embryo transferred, and the second re-frozen for a future cycle if it remains good quality.
Q: When can I schedule my transfer with donor embryos?
A: Clinics generally ask that you wait until the legal agreement is signed, since coordinating transport between clinics takes time. Once the embryos are at your clinic, you can plan your transfer on a timeline that works for you.
Have questions about receiving donor embryos or planning a transfer? Contact Embryo Connections and we will be glad to help.