October 2026. Written by Dr. Farhan. Associated with Ghazi Hospital. The date on your transfer summary still wins over a blank period box.
The front desk slides over a clipboard. First day of your last period. You had a medicated FET. There was no period that started this pregnancy. People freeze, then invent a date so the box is not empty. That invented date is how hospital software quietly moves an IVF due date.
What the form is actually asking
Most obstetric software still starts from a last menstrual period. It adds 280 days and prints a due date. That works when someone ovulated about two weeks after a real bleed. It does not describe a Day 5 blastocyst put in on a Thursday.
On the morning of a Day 5 transfer, standard charts already call you 2 weeks 5 days pregnant. That is 19 days of obstetric age before any home test. Day 3 transfer morning is 2 weeks 3 days. Retrieval or IUI is often counted as 2 weeks 0 days. Frozen time in the tank is not added. Our weeks-pregnant after transfer page uses the same offsets.
A concrete Day 5 example
Say the lab note says Day 5 blastocyst, transferred 12 March. The educational due date is 12 March plus 261 days. That is 266 days from fertilization, minus the five days the embryo already spent in culture.
If someone types a random March period into the LMP box, the portal can land a week off. A week is enough to move a first scan, an NIPT window, and the anatomy scan. It is also enough for the nurse to say your dates “do not match” when the transfer summary was fine.
You can check the same math on the IVF due date calculator before the appointment. Bring the printout. Do not bring a period-tracker screenshot unless that bleed is truly how your clinic dated you.
What to say out loud
Short version that front desks understand:
- “This is an IVF pregnancy. Please use the transfer date, not a last period.”
- “Embryo stage is Day 5” (or Day 3, Day 6, Day 7, retrieval, or IUI, whatever the embryology sheet says).
- “The due date on my transfer summary is [that date].”
- “I did not have a menstrual period that starts this pregnancy.”
If the software refuses to save without an LMP, ask them to back-calculate from the IVF due date and to type a comment: IVF, embryo day, transfer date. For a Day 5 transfer, that synthetic LMP is 19 days before transfer day. It is a software trick. It is not a bleed you had. Day 3 is 17 days before transfer. Retrieval or IUI is often 14 days before the procedure.
Do not round a Day 6 embryo to Day 5 because the dropdown only lists those two. Day 6 is one day earlier on the due date than Day 5. See Day 6 and Day 7 offsets.
Fresh cycle, FET, and donor eggs
A fresh transfer can still have a withdrawal bleed or a stim cycle that felt like a period. Dating still starts from retrieval or transfer plus embryo age, not from that bleed, unless your own clinic wrote a different rule on the summary.
A medicated frozen transfer often has no ovulation and no meaningful LMP at all. The thaw-and-transfer day is the anchor. The freeze date is not. Donor egg and donor embryo cycles use the same transfer-day rule. The donor’s age matters for other counseling. It does not change the 261-day Day 5 offset.
When a later scan disagrees
A first-trimester crown-rump length within about five to seven days of the IVF date usually keeps the transfer due date. A bigger gap is a conversation with the team that has the report, not a reason to reopen the period box. Later scans are weaker for dating. Read IVF due date vs ultrasound before you let a portal overwrite the transfer summary by itself.
Pregnancy apps fail the same way as the clipboard. They want a period. Why those apps get IVF wrong is the same mistake in a different font.
What not to do in the waiting room
- Do not pick “first day of bleeding after retrieval” unless your clinic dated you that way in writing.
- Do not use the trigger-shot night as an LMP.
- Do not average your IVF date with the ultrasound date to feel fair.
- Do not let a partner fill the box from memory while you are in the restroom.
Questions that come up at intake
They already saved the wrong date. Can I fix it?
Yes. Ask for the IVF due date to be restored from the transfer summary, with embryo day in the note. One wrong LMP can echo into referral letters, so check the after-visit summary before you leave.
Twins?
Same transfer date for both, unless your team documents a different plan. Two heartbeats do not create two last periods.
Does stopping progesterone change the form?
No. Luteal support has an end date on a medication list. It does not move the due date.
Related: Due date calculator · Weeks after transfer · First ultrasound
Educational only, not a clinic chart. If your team dated you from a trigger or a measured scan on purpose, follow that written plan.
Educational guide only — not medical advice. If your clinic chart disagrees with a date here, use the clinic chart. For pain, heavy bleeding, or fever, call your clinic’s after-hours line.