Calculators

IVF Due Date Calculator

Due date from your embryo transfer, egg retrieval or IUI, not from a last period you did not have.

How it works

A pregnancy lasts about 266 days from conception, or 280 from the first day of the last menstrual period. With natural conception the conception date has to be guessed from a cycle. With IVF it is known: a day-5 blastocyst was fertilised five days before it was transferred, whether fresh or frozen. So the calculator steps back to the moment of fertilisation and counts forward 266 days. Egg retrieval and IUI take place on the day of fertilisation, so no adjustment is needed.

due date = procedure date − embryo age + 266 days
embryo age
Days since fertilisation: 3, 5 or 6 for a transfer, 0 for retrieval or IUI
266 days
38 weeks, the average from conception to birth
LMP
Last menstrual period, the date obstetric dating wheels work from

Worked example

A frozen day-5 blastocyst transferred on September 1, 2026.

  1. 1Fertilisation was 5 days earlier: August 27, 2026
  2. 2Add 266 days: May 20, 2027
  3. 3Equivalent LMP is 14 days before fertilisation: August 13, 2026
  4. 4First blood test around 9 days after transfer: September 10, 2026

An estimated due date of May 20, 2027, the same date a natural pregnancy with an August 13 LMP would be given.

Frequently asked questions

Does a frozen transfer change the due date?

No. Freezing pauses an embryo's development, so a day-5 blastocyst is still five days past fertilisation when it is thawed and transferred, however long it was stored. Fresh and frozen transfers of the same embryo age give the same due date from the transfer day.

How many weeks pregnant am I at transfer?

By convention a pregnancy is dated from the equivalent LMP, two weeks before conception. On the day of a day-5 transfer you are therefore counted as 2 weeks and 5 days pregnant, and after a day-3 transfer 2 weeks and 3 days. This can be surprising, but it keeps IVF pregnancies on the same scale as every other.

When should I take a pregnancy test after transfer?

Clinics usually schedule a beta hCG blood test 9 to 11 days after a day-5 transfer, or 11 to 14 days after a day-3 transfer. Home tests taken earlier can give false negatives. If a trigger shot of hCG was part of your cycle, it can linger for up to two weeks and cause a false positive.

Are twins due earlier?

The due date is calculated the same way, but twins are born earlier on average, typically around 36 to 37 weeks rather than 40. Your care team will plan monitoring and delivery around that. Transferring a single embryo is now the norm at most clinics partly to avoid the risks of multiple pregnancy.

Related calculators

More in Health & Fitness