IVF due-date calculation from embryo transfer

ACOG recommends using the age of the embryo and transfer date to assign the EDD for an IVF pregnancy. These known treatment details are more specific than an LMP assumption.

Do not average the IVF date with an LMP date, add a cycle adjustment, or move the result to match a later ovulation estimate.

Check the clinic record for the transfer date and whether the embryo was day 3 or day 5. A two-day input difference creates a two-day EDD difference.

If you are unsure which embryo age applies, ask the fertility clinic rather than guessing from the calendar.

The EDD represents 40+0. For another date, subtract the days remaining to the EDD from 280, then express the result as complete weeks and remaining days.

Use calendar dates rather than elapsed clock hours so daylight-saving transitions do not shift the answer.

Early ultrasound remains important in clinical care, but ACOG says ART-derived gestational age should be used to assign the EDD.

Do not use an online scan calculator to redetermine an IVF due date. Bring any discrepancy to the fertility or maternity care team.

A known transfer date improves the dating basis; it does not predict the day labour will begin. EDD remains a reference date for organizing care, appointments, and a consistent gestational timeline.

Use the clinic's documented EDD as the source of truth in trackers and planning.

Take a day-5 embryo transfer on 1 January 2026. Adding 261 calendar days produces an EDD of 19 September 2026. A day-3 transfer on the same date adds 263 days and produces 21 September. The two-day difference follows directly from the embryo age at transfer.

To describe gestational age on a later date, treat the EDD as 40+0, count how many calendar days remain until it, and subtract that number from 280. Divide the result into completed weeks and remaining days. The arithmetic should use date-only values so a daylight-saving transition cannot create a false extra or missing day.

This example explains the convention; it cannot interpret a treatment record. If the clinic documents a different EDD, use the clinic's date and ask how it was established rather than modifying the transfer details until the calculator agrees. Store the clinic date in the pregnancy tracker so later week labels remain consistent.