IVF Birth Calculator
Ivf birth calculator works out Estimated due date and Day of the week from Embryo transfer date and Embryo age at transfer. The default figures on this page give estimated due date of 2026-11-26; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
5 steps
- Fertilisation is the embryo's day 0: 2026-03-10 - 5 day(s) = 2026-03-05.
- Estimated due date = transfer date + 266 - 5 = transfer + 261 days.
- ART pregnancies are dated by embryo age, so the dating LMP is fixed at conception - 14 = 2026-02-19 regardless of the patient's own cycle length.
- Estimated due date = 2026-11-26 (Thursday).
- On 2026-09-14 the pregnancy is 207 days from the dating LMP, i.e. 29w 4d.
Dating milestonestable
| label | gestationalAge | date |
|---|---|---|
| End of first trimester | 13 6/7 weeks | 2026-05-27 |
| Start of second trimester | 14 0/7 weeks | 2026-05-28 |
| Anatomy scan window opens | 18 0/7 weeks | 2026-06-25 |
| Limit of periviability | 24 0/7 weeks | 2026-08-06 |
| Start of third trimester | 28 0/7 weeks | 2026-09-03 |
| Early term begins | 37 0/7 weeks | 2026-11-05 |
| Full term begins | 39 0/7 weeks | 2026-11-19 |
| Estimated due date | 40 0/7 weeks | 2026-11-26 |
| Late term begins | 41 0/7 weeks | 2026-12-03 |
| Postterm begins | 42 0/7 weeks | 2026-12-10 |
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
What the ivf birth calculator calculates
Estimates the due date from the last menstrual period, a known conception date, an ultrasound gestational age or an IVF embryo transfer, with gestational age, trimester and term milestones.
How to use this ivf birth calculator
Enter Embryo transfer date and Embryo age at transfer. Estimated due date updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Estimated due date, Day of the week and Dating LMP.
The method follows ACOG Committee Opinion No. 700: Methods for Estimating the Due Date, ACOG Committee Opinion No. 579: Definition of Term Pregnancy and Parikh MN et al., Prediction of the date of confinement in women with cycles other than 28 days.
What you can compare
Change one input at a time to see how it affects Estimated due date, Day of the week and Dating LMP. The inputs you can vary are Embryo transfer date and Embryo age at transfer.
Understanding Estimated due date, Day of the week and Dating LMP
An estimate from calendar arithmetic, not a clinical assessment. Only about 4% of births occur on the estimated due date; ultrasound dating by a clinician supersedes menstrual dating when they disagree.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
Do IVF babies come closer to due date?
Estimates the due date from the last menstrual period, a known conception date, an ultrasound gestational age or an IVF embryo transfer, with gestational age, trimester and term milestones. Put your own figures in above and the working updates beside the result. For scale, the default figures on this page give 2026-11-26.
How do I calculate the due date for IVF twins?
Estimates the due date from the last menstrual period, a known conception date, an ultrasound gestational age or an IVF embryo transfer, with gestational age, trimester and term milestones. Open “How this is worked out” beside the result to see each step for your own figures.
What is the average week of birth for IVF babies?
On the figures this page opens with, the estimated due date is 2026-11-26. No single number fits everyone: it follows Embryo transfer date and Embryo age at transfer, so enter your own above and the answer updates as you type.
How accurate is your due date with IVF?
The ivf birth calculator follows the stated method, but the result is only as reliable as Embryo transfer date, Embryo age at transfer and Show progress as of and the assumptions shown. Check the working and sources before relying on it for an important decision.
Why are IVF babies usually boys?
It needs Embryo transfer date and Embryo age at transfer. Nothing else is required, and the figures stay in your browser.
What information do I need for the ivf birth calculator?
You need Embryo transfer date and Embryo age at transfer. The page opens with default figures that give estimated due date of 2026-11-26, so you can see the scale before entering your own.