This article is for general educational purposes only and does not constitute medical advice or a guarantee of outcomes. Exact timelines and protocols vary by individual case. Please consult a qualified specialist for advice about your own treatment plan.
A frozen embryo transfer (FET) has a gentler pace than a fresh IVF cycle — there’s no egg retrieval, no stimulation injections racing against your ovaries. Instead, the whole cycle is built around one goal: preparing your uterine lining to receive an embryo that’s already safely frozen. Most FET cycles span 2 to 3 weeks, and exactly how those weeks unfold depends on which of three protocols your clinic uses.
The Core Fact
There are three common FET protocols — medicated, natural, and modified natural — and each reaches the same destination by a slightly different route. Your clinic chooses based on your cycle regularity and medical history.
The Medicated FET Timeline
The most common approach, using estrogen and progesterone to build and time the lining directly — useful when your clinic wants full control over the schedule.
| Day | What's Happening |
|---|---|
| Day 1 | Baseline ultrasound and bloodwork; estrogen begins to prepare the lining. |
| Day 2–9 | Daily estrogen continues, thickening and stabilizing the endometrium. |
| Day 10 | Lining check and hormone labs confirm readiness for progesterone. |
| Day 11–15 | Progesterone starts (timed 3 days before a Day 3 transfer, or 5 days before a blastocyst transfer). |
| Day 16 | Embryo transfer — a quick, painless procedure. |
Worth holding onto: “Day 1” here means day 1 of your treatment cycle, usually day 2–5 of your actual period — not day 1 of your menstrual cycle.
The Natural FET Timeline
No medication, your own cycle —
Baseline monitoring starts around day 2–4 of your period. Your body's own hormones build the lining, with no estrogen or progesterone added.
Monitoring for ovulation —
From around day 10, follicle growth, lining thickness, and hormone levels are tracked until your LH surge confirms ovulation.
Transfer timed to ovulation —
The embryo is transferred 3 days after ovulation for a Day 3 embryo, or 5 days after for a blastocyst.
Myth: A natural FET is always a better or more “authentic” option than a medicated one.
Fact: Neither protocol is inherently superior — the choice depends on your cycle regularity and clinical picture. A medicated cycle simply gives the clinic more control over timing.
Not Sure Which FET Protocol Fits You?
Your cycle history and clinical picture determine the right approach — a consultation can map out your specific timeline.
The Modified Natural FET Timeline
A middle path — your natural cycle does most of the work, but a small amount of medication adds precision to the timing.
1. Letrozole (Days 1–5, If Used)
Supports follicle growth early in the cycle, taken alongside baseline monitoring.
2. Monitoring (Days 6–14)
Follicle size, lining thickness, and hormones are tracked as the follicle matures naturally.
3. Trigger Shot and Transfer
A trigger shot precisely times ovulation; the embryo is transferred 3–5 days later depending on its stage.
After the Transfer
Across all three protocols, the days after transfer look similar: a mid-way blood test checks that your hormone levels are supporting the pregnancy, and a beta hCG blood test follows 10–14 days after transfer. If the result is positive, progesterone (and sometimes estrogen) support typically continues through 8–12 weeks of pregnancy before you transition to routine obstetric care.
Three different roads, one destination — a lining ready to receive your embryo.
Frequently Asked Questions
1. How long does a frozen embryo transfer cycle take?
Most FET cycles span 2 to 3 weeks from the start of monitoring to transfer day, though the exact length depends on your protocol and how your lining responds to preparation.
2. What's the difference between a medicated and natural FET?
A medicated FET uses estrogen and progesterone to build and time the uterine lining directly. A natural FET relies on your body’s own cycle and hormones, with monitoring used to time the transfer around ovulation.
3. Why is the embryo transferred 3 or 5 days after progesterone starts?
The timing matches the embryo’s stage at freezing — 3 days of progesterone support before a Day 3 (cleavage-stage) transfer, or 5 days before a blastocyst (Day 5) transfer.
4. What happens if my lining isn't thick enough on the monitoring visit?
Your clinic may extend estrogen or monitoring for a few more days before moving to progesterone and transfer — this is a normal adjustment, not a sign the cycle has failed.
5. When is the pregnancy test done after a frozen embryo transfer?
A beta hCG blood test is typically done 10 to 14 days after transfer, regardless of which FET protocol was used.
- Get Your Personalised FET Timeline
Every protocol is tailored to your cycle — a consultation maps out exactly what your own frozen transfer will look like.