IVF Due Date Calculator

About the IVF Due Date Calculator

IVF pregnancies are usually dated more precisely than spontaneous pregnancies because the embryo age and transfer date are known. This calculator uses those two details to estimate the due date from either a Day-3 cleavage-stage transfer or a Day-5 blastocyst transfer.

For a Day-3 transfer, the due date is the transfer date plus 263 days. For a Day-5 transfer, it is the transfer date plus 261 days. The same logic applies to both fresh transfers and frozen embryo transfers: the important inputs are the transfer date and the embryo age on that date.

Use this estimate to line up prenatal milestones, screening windows, and gestational-age tracking with the IVF dating method your clinic and OB team already use.

When This Page Helps

IVF dating is usually the cleanest starting point because it does not rely on assumptions about ovulation timing or cycle length. That makes it the best reference for first-trimester screening windows, anatomy-scan timing, gestational-age labels, and due-date planning from the start of pregnancy.

How to Use the Inputs

1. Enter the date your embryo transfer was performed.
2. Select whether you had a Day-3 (cleavage stage) or Day-5 (blastocyst) transfer.
3. View your estimated due date, LMP equivalent, and current gestational age.
4. Share the results with your OB/GYN or reproductive endocrinologist for confirmation.
5. Use the gestational age to track your pregnancy milestones.

Example Calculation

Tips & Best Practices

• The transfer date is the date the embryo was placed in the uterus, not the retrieval or fertilization date.
• Day-5 transfers are the most common today and tend to have higher success rates than Day-3 transfers.
• Frozen embryo transfer (FET) uses the same calculation — the embryo age at freezing is what matters.
• Your clinic may provide an LMP-equivalent date; verify it matches this calculator's output.
• First-trimester ultrasound dating should closely match IVF-calculated dates — discrepancies may warrant discussion.
• Keep your transfer date documented for all future prenatal appointments.

How IVF Due Date Calculation Works

The standard gestation from fertilization to birth is 266 days. Since an IVF embryo's age is precisely known, we subtract the embryo age from 266 and add the result to the transfer date. For Day-5 blastocysts: 266 − 5 = 261 days. For Day-3 embryos: 266 − 3 = 263 days.

Fresh vs. Frozen Transfers

The calculation is identical for fresh and frozen embryo transfers. A Day-5 blastocyst that was frozen and thawed is still a Day-5 embryo on the day of transfer. The only date that matters is the day the embryo entered the uterus.

Why IVF Dates Are the Gold Standard

Reproductive endocrinologists consider IVF-derived due dates to be the most accurate available. The embryo's age is documented to the hour, and the transfer date is recorded precisely. Even early ultrasound measurements have a margin of error of 3-5 days, while IVF dating is accurate to within 1-2 days.

Frequently Asked Questions

• Why is IVF dating more accurate?

  In IVF, the exact day of fertilization and embryo transfer is documented by the clinic. This eliminates the guesswork about ovulation timing that affects LMP-based dating. The precision can be as close as 1-2 days.

• What's the difference between Day-3 and Day-5?

  A Day-3 embryo is at the cleavage stage (6-8 cells), while a Day-5 embryo is a blastocyst (100+ cells). Day-5 transfers allow more time to identify the healthiest embryos and have higher implantation rates. The due date differs by 2 days between the two.

• Does frozen vs. fresh transfer change the due date?

  No. Whether the embryo was fresh or frozen, the due date calculation is the same. The embryo's age at transfer (Day 3 or Day 5) is what determines the due date, not whether it was previously frozen.

• What is the LMP equivalent?

  The LMP equivalent is a calculated date that represents what your last menstrual period would have been if you conceived naturally. It is used for medical records and gestational age tracking. For Day-5: LMP = Transfer Date − 19 days.

• Should I adjust if my ultrasound date differs?

  For IVF pregnancies, most providers will keep the IVF-calculated date unless the ultrasound differs by more than 5-7 days, which is uncommon. IVF dating is typically more reliable than ultrasound dating.

• Can I use this for donor egg or embryo cycles?

  Yes, the calculation is the same regardless of whether you used your own eggs or donor eggs/embryos. The transfer date and embryo age at transfer are the only factors needed.

• What is gestational age at the time of transfer?

  At a Day-5 transfer, gestational age is 2 weeks and 5 days (14 + 5 = 19 days). At a Day-3 transfer, it is 2 weeks and 3 days. This accounts for the 14 days of the LMP-equivalent pre-ovulation period.

• How many weeks is a full-term IVF pregnancy?

  An IVF pregnancy is the same 40 weeks as a natural pregnancy, measured from the LMP equivalent. Full term is 39-40 weeks, with most IVF pregnancies delivering in the typical 37-42 week range.