IVF Due Date Calculator: Day-3, Day-5, FET and IUI

Your IVF due date

Pick the date you actually have on paper — embryo transfer, egg retrieval or IUI. For a transfer, choose how old the embryo was on that day: day 3 is a cleavage embryo, day 5 or 6 a blastocyst. Your clinic's discharge note says which.

Why your last period is the wrong starting point

An ordinary due date is worked out from the first day of the last period, because that is the only date most pregnancies have. It assumes conception happened about 14 days later, which is a guess that is often a few days out and sometimes a week.

In an IVF cycle there is nothing to guess: the egg was collected on a known date, the embryo was transferred on a known date, and the bleed before all that was brought on by medication. Feeding that bleed into an LMP calculator can put your due date two weeks out — on the one pregnancy where the date could have been exact.

How the date is worked out

Pregnancy is counted as 280 days from a notional last period, 14 days before conception. Egg retrieval is that conception moment, so a retrieval or an IUI is 266 days from the due date. An embryo transferred at five days old is already five days further on, so a day-5 transfer is 261 days.

That is the whole calculation, and it is why you are not "zero weeks pregnant" on transfer day: a day-5 transfer already counts as 2 weeks and 5 days.

Frozen or fresh makes no difference

A frozen transfer is dated exactly like a fresh one. Time in the freezer does not age an embryo: a blastocyst frozen for two years is still five or six days old on the day it is transferred, and that age is the whole calculation. Donor eggs work the same way — the date comes from the embryo, not from the person who provided the egg.

When your doctor's date is different

Your doctor may re-date the pregnancy from the measurements at a scan. In an IVF pregnancy that is unusual, because the dating is already exact, and a large difference is worth asking about rather than assuming one of you is wrong.

If they do change it, their date is the one that counts: it drives when the anomaly scan is booked, when a glucose test is due, and when a doctor starts talking about induction.

Common questions