Enter your embryo transfer date and get the dates that follow from it: estimated due date, equivalent last period, trimester boundaries and the term window.
| Input | Result |
|---|---|
| Day-5 transfer on 10 March 2026 | Due 26 November 2026; equivalent LMP 19 February 2026 |
| Day-3 transfer on 10 March 2026 | Due 28 November 2026 |
| Egg retrieval on 10 March 2026 | Due 1 December 2026 |
An embryo transfer is one of the few moments in pregnancy where the calendar is known to the day. Everything else follows from it: the estimated due date, the equivalent last period your clinic will use when it talks about weeks, and the boundaries that define each trimester and term.
| Milestone | Counted from | Days from equivalent LMP |
|---|---|---|
| Equivalent last menstrual period | Due date | −280 |
| End of first trimester | Equivalent LMP | 97 (13+6) |
| End of second trimester | Equivalent LMP | 195 (27+6) |
| Early term begins | Equivalent LMP | 259 (37+0) |
| Estimated due date | Equivalent LMP | 280 (40+0) |
| Post-term | Equivalent LMP | 294 (42+0) |
These are obstetric conventions rather than predictions. Where your own scan dates a pregnancy differently by a day or two, an IVF date usually stands, but your care team makes the final call.
A natural-conception due date works backwards from the first day of your last period and assumes ovulation on day 14, an assumption that is wrong for a lot of people. IVF dating removes the guesswork, because the laboratory knows exactly how old the embryo was on the day it was transferred.
Everything follows from one rule. Convert the transfer date into an equivalent last menstrual period, then add the standard 280 days:
equivalent LMP = transfer date − (14 + embryo age in days)
due date = equivalent LMP + 280 days
which is the same thing as adding a fixed number of days to the transfer date:
| Starting point | Days to add | Why |
|---|---|---|
| Egg retrieval (day 0) | 266 | Retrieval stands in for ovulation, 14 days into a 280-day pregnancy |
| Day-5 embryo transfer | 261 | 266 − 5, the embryo is already five days old |
| Day-3 embryo transfer | 263 | 266 − 3 |
| Day-6 embryo transfer | 260 | 266 − 6 |
Clinical reference: ACOG Committee Opinion No. 700, Methods for Estimating the Due Date.
Not medical advice. This calculator does date arithmetic on the dates you enter, nothing more. It does not diagnose, does not assess a pregnancy and cannot account for your individual history. Your fertility clinic or midwife sets your official dating, and ultrasound findings can override any calculation. If anything here conflicts with what your care team told you, theirs is the date that counts.
Once the transfer date and embryo age are known, the whole pregnancy timeline follows: the estimated due date, the equivalent last menstrual period that clinics use for gestational age, the trimester boundaries and the 37-week to 42-week term window.
From an equivalent last menstrual period, which is the transfer date minus 14 days plus the embryo's age. That is why a pregnancy is already counted as roughly two weeks along at transfer, it keeps IVF pregnancies on the same scale as naturally conceived ones.
Term runs from 37+0 to 42+0 weeks, and that five-week span is where most babies actually arrive. Only about one in twenty is born on the due date itself, so the window is the useful number for planning leave, travel and support.
Yes, by two days. A day-5 embryo is two days further along, so its due date falls two days earlier than a day-3 embryo transferred on the same date.