FET Due Date Calculator: IVF Pregnancy Timeline Made Simple
A clear guide to calculating your due date for fresh and frozen embryo transfers, with simple formulas for Day 3, Day 5, and FET cycles.
IVF due dates can be hard to estimate without help. This guide explains how to calculate your pregnancy timeline based on embryo transfer type, embryo age, and key milestones. It's written for both patients and providers.
Calculate your precise IVF due date now
Our calculator supports all IVF scenarios: Day 3 transfers, Day 5 transfers, frozen embryo transfers (FET), and even calculation from retrieval date.
In natural conception, due dates are estimated based on the first day of your last menstrual period (LMP). With IVF, we use the exact date the embryo was transferred into the uterus. That means the calculation is more accurate.
Instead of estimating when ovulation happened, we adjust your pregnancy timeline based on:
How old the embryo was on transfer day
Whether the embryo was fresh or frozen
The IVF Pregnancy Timeline (Month by Month)
Here's how your pregnancy typically progresses after transfer:
2 Weeks After Transfer: Blood test confirms pregnancy (beta hCG)
4–5 Weeks: First ultrasound can detect a gestational sac
6–7 Weeks: Heartbeat may be visible
10–12 Weeks: NIPT and genetic screenings available
12 Weeks: First trimester ends
18–20 Weeks: Anatomy scan
28 Weeks: Third trimester begins
40 Weeks: Estimated due date
Day 3 vs. Day 5 Embryo Transfers: Calculation Differences
Your due date depends on how developed your embryo was on transfer day. Here's what you need to know:
Day 3 embryos are less developed (6-8 cells) and need 2 more days of growth
Day 5 embryos (blastocysts) are more developed (100+ cells) and already 2 days ahead
This is why the due date is 2 days earlier for day 5 transfers compared to day 3
The difference in calculation (263 days vs. 261 days) directly reflects the additional development time that occurs between day 3 and day 5:
Day 3 embryos have 2 more days of development to complete compared to day 5 embryos
Day 5 embryos (blastocysts) are already further developed, so their pregnancy timeline is 2 days ahead
This 2-day difference is maintained throughout the pregnancy and is reflected in the final due date calculation. It's important to specify which type of embryo you had transferred when using any due date calculator.4
Clinical Success Rates Comparison
While not directly related to due date calculation, it's worth noting that day 5 blastocyst transfers generally have higher implantation rates than day 3 transfers. This is because embryos that successfully develop to the blastocyst stage have demonstrated viability and developmental competence. However, not all embryos will successfully develop to day 5, which is why day 3 transfers remain an important option for many patients.5
For due date calculation purposes, the key point is that the embryo's developmental age at transfer (3 or 5 days) must be factored into the calculation to obtain an accurate expected delivery date.
Frozen Embryo Transfers (FET): Special Considerations
For frozen embryo transfers (FETs), calculating your due date is simple. What matters is how old your embryo was when it was frozen - not how long it was frozen.
Quick FET Due Date Guide
To find your due date for a frozen embryo transfer, just follow this simple rule:
For day 3 embryos frozen and then transferred: Transfer date + 263 days
For day 5 embryos (blastocysts) frozen and then transferred: Transfer date + 261 days
The duration of freezing does not affect the due date calculation. Whether an embryo was frozen for 1 month or 5 years, the calculation remains the same.6
Natural vs. Programmed FET Cycles
There are two primary protocols for preparing the uterine lining for FET:
FET Protocol Comparison
Protocol Type
Description
Due Date Calculation Impact
Natural Cycle FET
Uses woman's natural menstrual cycle; transfer timed with natural ovulation
No difference in calculation method
Programmed/Medicated FET
Uses hormonal medications to prepare the uterine lining without ovulation
No difference in calculation method
While these different protocols affect how the transfer is scheduled, they do not change the fundamental due date calculation, which is based solely on the embryo's developmental age and the transfer date.7
Benefits of FET for Due Date Accuracy
Some reproductive endocrinologists believe FET cycles may offer even more precision in due date calculation than fresh transfers. This is because:
The uterine environment in FET cycles may more closely resemble a natural cycle compared to the hormonally stimulated environment following egg retrieval
FET protocols can be precisely timed to optimize implantation conditions
Embryo quality assessment prior to freezing adds another layer of selection
Research suggests that FET pregnancies may have slightly lower risks of certain complications and better birth weights compared to fresh transfer pregnancies, though differences in due date accuracy between fresh and frozen transfers are minimal.8
Step-by-Step IVF Due Date Calculation Examples
Let's walk through specific examples to illustrate exactly how IVF due dates are calculated in different scenarios. These examples will help clarify the formulas discussed in previous sections.
Example 1: Day 5 Fresh Embryo Transfer
Scenario: Egg retrieval on May 1, 2025, with a day 5 blastocyst transfer on May 6, 2025.
Identify the transfer date: May 6, 2025
Determine embryo age at transfer: 5 days
Apply the formula: Transfer date + 261 days
Calculate: May 6, 2025 + 261 days = January 22, 2026
Expected due date: January 22, 2026
Alternative calculation from retrieval date: Retrieval date (May 1, 2025) + 266 days (38 weeks) = January 22, 2026
Example 2: Day 3 Fresh Embryo Transfer
Scenario: Egg retrieval on June 15, 2025, with a day 3 embryo transfer on June 18, 2025.
Identify the transfer date: June 18, 2025
Determine embryo age at transfer: 3 days
Apply the formula: Transfer date + 263 days
Calculate: June 18, 2025 + 263 days = March 8, 2026
Expected due date: March 8, 2026
Alternative calculation from retrieval date: Retrieval date (June 15, 2025) + 266 days (38 weeks) = March 8, 2026
Example 3: Frozen Embryo Transfer (Day 5 Blastocyst)
Scenario: A day 5 blastocyst was frozen after retrieval. FET performed on August 10, 2025.
Identify the transfer date: August 10, 2025
Determine embryo age at freezing: 5 days
Apply the formula: Transfer date + 261 days
Calculate: August 10, 2025 + 261 days = April 28, 2026
Expected due date: April 28, 2026
Note: The original retrieval date does not factor into this calculation. The duration of freezing also has no impact on the due date.
Gestational Age Translation
When communicating with obstetricians, it's helpful to understand how to translate between IVF timing and standard obstetric dating:
At transfer, a day 3 embryo is considered 2 weeks + 3 days gestational age
At transfer, a day 5 embryo is considered 2 weeks + 5 days gestational age
The first ultrasound (typically 6-7 weeks gestational age) occurs 3-4 weeks after embryo transfer
This translation helps ensure that all healthcare providers are using the same terminology and timeline during your prenatal care.9
How to Use the IVF Due Date Calculator
Choose your embryo transfer type:
Day 3 transfer: Embryo is 3 days old at implantation
Day 5 transfer: Embryo is more mature (blastocyst)
FET (frozen embryo transfer): Embryo was frozen, then thawed and transferred later
Then enter your transfer date. The calculator will show:
Your estimated due date
Trimester milestones
Important prenatal appointment windows
Related Fertility Tools
For a more comprehensive understanding of fertility and pregnancy, we offer several related calculators and resources that complement our IVF Due Date Calculator:
Fertility After 35
Understanding age-related fertility decline, success rates, and strategies for conception later in life.
An IVF due date uses the embryo's age and transfer date instead of last period date. The simple formula is:
Day 5 embryos: Transfer date + 261 days
Day 3 embryos: Transfer date + 263 days
For frozen embryos (FET): Same formula based on embryo age when frozen
Are IVF due dates more accurate than natural conception due dates?
Yes, IVF due dates tend to be more accurate than those from natural conception because the exact age of the embryo is known. In natural conception, due dates are estimated from the last menstrual period, assuming a 28-day cycle and ovulation on day 14, which isn't accurate for many women. However, even with IVF, only about 5% of births occur exactly on the calculated due date, as other factors influence delivery timing.
What's the difference between day 3 and day 5 embryo transfers for due date calculation?
The main difference is their development stage:
Day 3 embryos have 6-8 cells and need 2 more days of growth
Day 5 embryos (blastocysts) have 100+ cells and are already more developed
This is why day 5 transfer due dates are 2 days earlier than day 3 transfers (add 261 days vs. 263 days).
Does a frozen embryo transfer (FET) affect my due date calculation?
No! Use exactly the same formula as fresh transfers:
Day 5 frozen embryo: Transfer date + 261 days
Day 3 frozen embryo: Transfer date + 263 days
It doesn't matter if your embryo was frozen for 1 month or 5 years - the calculation stays the same.
Why is my gestational age different from my embryo's actual age?
Doctors always add 2 weeks to your embryo's actual age to get "gestational age." This is because in natural pregnancies, they count from the last period (about 2 weeks before conception). With IVF, they keep this system so all pregnancies use the same timeline.
Here's a simple conversion:
Day of egg retrieval = 2 weeks pregnant
Day 3 embryo at transfer = 2 weeks + 3 days pregnant
Day 5 embryo at transfer = 2 weeks + 5 days pregnant
Can I calculate my due date from my egg retrieval date?
Yes! This is actually the simplest method:
Egg retrieval date + 266 days (38 weeks) = Due date
This works for both day 3 and day 5 transfers, since it starts from fertilization day (when eggs were retrieved and fertilized).
Should I tell my obstetrician that I conceived through IVF?
Yes, always tell your OB you conceived through IVF and provide:
Your embryo transfer date
Whether it was day 3 or day 5
Whether it was fresh or frozen
This helps them date your pregnancy accurately and provide better care throughout your pregnancy.
Scientific References
Cooke, I., et al. (2018). "Gestational dating in IVF pregnancies: a cohort study evaluating early obstetric ultrasound vs. embryo transfer dating." Fertility and Sterility, 110(4), 654-659.
American College of Obstetricians and Gynecologists (2021). "Methods for Estimating the Due Date." ACOG Committee Opinion No. 700.
Zegers-Hochschild, F., et al. (2017). "The International Glossary on Infertility and Fertility Care." Human Reproduction, 32(9), 1786-1801.
Maheshwari, A., et al. (2016). "Obstetric and perinatal outcomes in singleton pregnancies resulting from the transfer of blastocyst-stage versus cleavage-stage embryos generated through in vitro fertilization treatment: a systematic review and meta-analysis." Fertility and Sterility, 106(6), 1244-1254.
Glujovsky, D., et al. (2016). "Cleavage stage versus blastocyst stage embryo transfer in assisted reproductive technology." Cochrane Database of Systematic Reviews, 6, CD002118.
Wong, K.M., et al. (2017). "Fresh versus frozen embryo transfers in assisted reproduction." Cochrane Database of Systematic Reviews, 3, CD011184.
Groenewoud, E.R., et al. (2016). "A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer." Human Reproduction, 31(7), 1483-1492.
Sha, T., et al. (2018). "Pregnancy-related complications and perinatal outcomes resulting from transfer of cryopreserved versus fresh embryos in vitro fertilization: a meta-analysis." Fertility and Sterility, 109(2), 330-342.
Annan, J.J., et al. (2019). "Effect of embryo transfer day on pregnancy outcomes: a review of the literature." Journal of Assisted Reproduction and Genetics, 36(10), 2165-2171.
Stormlund, S., et al. (2020). "Freeze-all versus fresh blastocyst transfer strategy during in vitro fertilisation: multicentre randomised controlled trial." BMJ, 370, m2519.