Frozen Embryo Transfer Timeline: The FET Cycle Day by Day
By Emily Johnson, Content Writer & Fertility Advocate · Medically reviewed by Dr. Sarah Ahmed, Medical Content Advisor
Table of Contents
A frozen embryo transfer (FET) cycle usually takes about three to six weeks from the first day of your period to transfer day, and the exact frozen embryo transfer timeline depends on which protocol your clinic uses. In a medicated cycle, hormones control the timing; in a natural cycle, your own ovulation sets the pace. This guide walks through each version day by day, so you know what happens at every scan, what your clinic is checking, and when your pregnancy test will be.
What Is a Frozen Embryo Transfer (FET)?
A frozen embryo transfer uses an embryo created during an earlier IVF cycle, frozen (vitrified) and stored, then thawed and transferred into the uterus in a later cycle. Because the embryo already exists, an FET cycle skips egg retrieval and fertilisation entirely — the whole cycle is about preparing the uterine lining, timing the transfer to the lining’s receptive window, and then supporting the luteal phase until the pregnancy test.
That is also why the FET timeline is shorter and gentler than a full fresh IVF cycle, and why it is a common next step after a fresh cycle or when embryos remain frozen. If you are comparing approaches, read our guide on fresh vs frozen embryo transfer and whether it changes your due date. For background on assisted reproductive technology, see the CDC’s overview of assisted reproductive technology (ART).
FET Timeline at a Glance
| Phase | Medicated FET (typical) | Natural FET (typical) |
|---|---|---|
| Cycle days 1–3 | Baseline scan and bloodwork; estrogen starts | Baseline scan and bloodwork |
| Days 10–14 | Lining check ultrasound | Ovulation monitoring (LH surge) |
| Days 14–16 | Progesterone starts once lining is ready | Ovulation confirmed |
| Days 19–22 | Transfer day (day 5 embryo, 5–6 days after progesterone starts) | Transfer day (5 days after ovulation for a day 5 embryo) |
| 9–14 days after transfer | Beta hCG blood test | Beta hCG blood test |
Every clinic’s protocol differs slightly, and your own cycle may run longer if your lining needs more time. The calendar never decides on its own — your lining thickness, hormone levels and embryo stage set the transfer day.
The Medicated (Hormone Replacement) FET Timeline Day by Day
The medicated cycle is the most common FET protocol because it gives your clinic precise control over timing. Your natural ovulation is suppressed or simply bypassed, and estrogen and progesterone are given in a planned sequence.
Days 1–3: Baseline Scan and Estrogen Begins
Day 1 is the first day of full menstrual flow. Around day 2 or 3 you will have a baseline ultrasound and bloodwork to confirm there are no cysts and that the lining has shed. Estrogen then starts — usually as tablets, patches or injections — to thicken the endometrium (uterine lining).
Days 10–14: Lining Check Ultrasound
After roughly 10–14 days of estrogen, you return for a lining check. Your clinic measures endometrial thickness and checks blood estrogen levels. Many clinics look for a lining around 7–8 mm or more with a healthy triple-line pattern, though the exact target varies by clinic. If the lining is still thin, estrogen continues for a few more days and the scan is repeated — your embryo stays safely frozen while you wait.
Days 15–16: Progesterone Starts
Once the lining is ready, progesterone begins — as injections, vaginal suppositories or gel. Progesterone changes the lining from the growth phase to the receptive phase and opens the window of implantation. The transfer is timed precisely from the first progesterone dose, which is why this date matters so much.
Days 20–22: Transfer Day
For a day 5 embryo (blastocyst), transfer usually happens on the 6th day of progesterone; for a day 3 embryo, on the 4th day. On transfer day, the embryologist thaws your embryo, checks that it has survived the thaw and resumed development, and your doctor places it into the uterus through a thin catheter guided by ultrasound. The procedure is usually quick and painless. See the full day-by-day account in our transfer-day section below.
Days 1–14 After Transfer: Support and the Beta Test
You keep taking estrogen and progesterone exactly as prescribed until the pregnancy test, and usually beyond it if the test is positive. A beta hCG blood test is done about 9–14 days after transfer — most clinics test around day 9–12 for a day 5 embryo. Our guide on when to take a pregnancy test after IVF explains the day-by-day hCG picture.
The Natural Cycle FET Timeline Day by Day
A natural cycle FET suits people with regular ovulation. It uses little or no medication and follows your body’s own rhythm, which means more monitoring visits but fewer drugs.
Days 1–3: Baseline and Monitoring Begins
As with a medicated cycle, day 1 is the first day of your period and a baseline scan confirms a clean start. From around day 10, you attend monitoring scans and blood tests to track the dominant follicle and the LH surge that triggers ovulation.
Days 14–16: Ovulation Confirmed
Ovulation is confirmed by ultrasound and bloodwork. This is the anchor date for the whole natural FET timeline: a day 5 embryo is transferred 5 days after ovulation, and a day 3 embryo 3 days after ovulation.
Days 19–21: Transfer Day
Transfer typically falls on days 19–21 of the cycle for a day 5 embryo. Progesterone support may be added after ovulation, depending on your clinic’s protocol.
Days 1–14 After Transfer: The Two-Week Wait
The two-week wait works the same way as in a medicated cycle — continue any prescribed progesterone, then a beta hCG test about 9–14 days after transfer. Our day-by-day two-week wait guide covers what to expect each day.
Modified Natural FET Timeline
A modified natural cycle is a middle path: your own ovulation is tracked, but a trigger injection (hCG) is used to control the exact timing of ovulation, and progesterone support is usually added. The timeline looks much like a natural cycle — baseline, monitoring from around day 10, trigger, then transfer 5 days after ovulation for a blastocyst — with the advantage of a more predictable transfer date and fewer surprise weekend procedures. Clinics often choose this option when cycles are mostly regular but timing needs tightening.
Day 3 vs Day 5 Embryo: How Transfer Day Shifts
The embryo’s stage changes the transfer date in every protocol, because the embryo and the lining must be in sync.
| Embryo stage | Medicated FET | Natural FET |
|---|---|---|
| Day 3 embryo (cleavage stage) | 4th day of progesterone | 3 days after ovulation |
| Day 5 embryo (blastocyst) | 6th day of progesterone | 5 days after ovulation |
For example, if progesterone starts on day 15 of a medicated cycle, a day 3 embryo would be transferred around day 18 and a day 5 embryo around day 20–22. Our comparison of day 3 vs day 5 transfer explains how the stage also affects due date calculation.
What Happens on Transfer Day
Transfer day itself is short, but several steps happen in order:
- Thawing and assessment. The embryologist thaws the embryo in the morning and checks survival and continued development under the microscope. Most vitrified blastocysts survive thawing well; if an embryo does not survive, your clinic will tell you before the procedure and discuss any backup embryos.
- Preparation. You will usually arrive with a comfortably full bladder, which helps the ultrasound view during the procedure.
- The transfer. Using a thin, soft catheter passed through the cervix under ultrasound guidance, the doctor places the embryo into the uterus. It takes only a few minutes and is generally painless.
- Rest and going home. A short rest follows, and you can usually go home the same day. There is no evidence that strict bed rest after transfer improves outcomes — normal, gentle activity is fine unless your clinic advises otherwise.
After Transfer: The Two-Week Wait Day by Day
The two-week wait runs from transfer day to the beta test. In the first few days the embryo, if it implants, begins producing hCG; by days 9–14 after a day 5 transfer, a blood test can reliably detect it. Home pregnancy tests can turn positive earlier, but they are less reliable and can be misleading — especially if you had an hCG trigger injection, which can cause a false positive. Wait for your clinic’s beta test date, and read our beta hCG levels chart for what the numbers mean.
When Things Don’t Go to Plan
Not every FET cycle reaches transfer day on the first schedule, and a delay is not a failure:
- Thin lining. If the lining stays thin, estrogen continues and the scan is repeated. If it stays thin across cycles, your clinic will investigate causes such as scarring inside the uterus before trying again.
- Early ovulation in a medicated cycle. A blood test before progesterone checks that you have not ovulated early. If you have, the cycle is usually stopped and your embryo stays safely frozen for the next attempt.
- Embryo does not survive thawing. This is uncommon with modern vitrification, but if it happens, your clinic will discuss backup embryos or a new stimulation cycle.
- Negative beta test. A negative result ends that cycle’s medication, and your clinic will review the protocol — lining, timing, embryo quality — before planning the next transfer.
How Your FET Timeline Affects Your Due Date
Your due date after a frozen transfer is calculated from the transfer date, not from your last period, because ovulation was controlled or replaced. As a rule of thumb, a day 5 transfer date plus 261 days gives the estimated due date (a day 3 transfer uses 263 days), and ultrasound dating later in pregnancy can refine it. Work it out exactly with our frozen embryo transfer due date calculator — and if you are tracking pregnancy week by week, see how many weeks pregnant you are after embryo transfer.
Frequently Asked Questions
How long does a frozen embryo transfer cycle take?
Most FET cycles take about three to six weeks from day 1 of your period to transfer day. A medicated cycle is usually around four to five weeks, while a natural cycle follows your own ovulation and typically reaches transfer on days 19–21.
On which day of the cycle is a frozen embryo transfer done?
Usually around days 19–22, counting day 1 as the first day of your period. In a medicated cycle the exact day is set by progesterone timing — the 6th day of progesterone for a day 5 embryo — while in a natural cycle it is 5 days after ovulation.
What is the difference between a medicated and a natural FET?
A medicated FET uses estrogen and progesterone to control the lining and timing precisely. A natural FET follows your own ovulation with little or no medication. A modified natural FET tracks natural ovulation but adds a trigger injection for timing control.
How thick should the lining be before a frozen embryo transfer?
Many clinics look for around 7–8 mm or more with a healthy pattern, but targets vary by clinic. If the lining is thin, estrogen is continued and the scan repeated — the embryo stays frozen until the lining is ready.
When is the pregnancy test after a frozen embryo transfer?
A beta hCG blood test is usually done 9–14 days after transfer. Home tests can turn positive earlier but are less reliable, and an hCG trigger injection can cause a false positive, so your clinic’s blood test date is the one that counts.
What happens if my lining stays thin during an FET cycle?
Your clinic gives estrogen more time and rechecks the lining. If it stays thin across cycles, they will look for an underlying cause, such as scarring inside the uterus, before attempting another transfer.
Do I need bed rest after a frozen embryo transfer?
No strict bed rest is needed. A short rest after the procedure is normal, and gentle everyday activity is fine unless your clinic advises otherwise — there is no evidence that bed rest improves implantation.
Does a frozen embryo transfer change my due date?
Yes — the due date is calculated from the transfer date and the embryo’s stage, not from your last period. A day 5 transfer date plus 261 days gives the estimated due date, and ultrasound dating can refine it later.
About the Author
Emily Johnson is a Content Writer & Fertility Advocate who covers IVF and fertility treatment topics. Meet the team.
Medical Review
This article was medically reviewed by Dr. Sarah Ahmed, Medical Content Advisor, for clinical accuracy. Meet the team.
Medical Disclaimer
This article is for informational purposes only and is not medical advice, diagnosis, or treatment. Due dates are estimates, and every pregnancy is different. Always confirm your due date and any testing or treatment decisions with your clinic or healthcare provider.
