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✓ ACOG ART dating✓ Day 2, 3, 5 & 6✓ Twins & triplets

IVF, FET & IUI Due Date Calculator: Day 3, Day 5, Day 6 & Twins

Enter your embryo transfer, egg retrieval or IUI date to get your exact due date, how many weeks pregnant you are today, and every key scan and test date — including twins and triplets.

✓ Medically referenced & last reviewed: 13 Nov 2026

🧬 IVF / FET / IUI Due Date Calculator

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IVF, FET & IUI Due Date Formula Table (Day 3 vs Day 5)

Because the exact date of fertilization is known in IVF, IVF dating is the most accurate of all methods. A pregnancy lasts 266 days from conception (280 days from the equivalent LMP). An embryo that is already 5 days old on transfer day therefore needs 266 − 5 = 261 days.

MethodDue date (EDD)Equivalent LMP
Day-2 embryo transferTransfer + 264 daysTransfer − 16 days
Day-3 embryo transferTransfer + 263 daysTransfer − 17 days
Day-5 blastocyst (fresh or FET)Transfer + 261 daysTransfer − 19 days
Day-6 blastocyst (FET)Transfer + 260 daysTransfer − 20 days
Egg retrieval / ICSIRetrieval + 266 daysRetrieval − 14 days
IUIIUI + 266 daysIUI − 14 days
Natural (ovulation)Ovulation + 266 daysOvulation − 14 days
ACOG recommends that pregnancies conceived with assisted reproductive technology are dated from the embryo age and transfer date, and that this date is not changed by later ultrasound measurements.

IVF Twins, Pregnancy Weeks & What Happens Next

  • Weeks of pregnancy are counted from the equivalent LMP — so on the day of a Day-5 transfer you are already 2 weeks 5 days pregnant.
  • Twins occur in about 20–30% of double-embryo transfers but only ~1–2% of single-embryo transfers (mostly identical splits). Single embryo transfer is recommended for most patients.
  • Twins are usually delivered at 36–38 weeks (dichorionic) or 34–37 weeks (monochorionic); triplets around 32 weeks.
  • Continue progesterone/estrogen support exactly as your clinic prescribes, usually until 8–12 weeks.

Frequently Asked Questions

How do you calculate an IVF due date?
Add 266 days to the fertilization (egg retrieval) date, or subtract the embryo’s age from 266 and add that to the transfer date: Day-3 transfer + 263 days, Day-5 transfer + 261 days, Day-6 transfer + 260 days.
How many weeks pregnant am I after a Day-5 transfer?
On transfer day you are 2 weeks 5 days pregnant. Nine days later (9dp5dt, the usual beta test) you are 4 weeks 0 days.
Is a frozen embryo transfer (FET) due date calculated differently?
No. It uses the embryo age at transfer, exactly like a fresh transfer. The date the embryo was frozen does not matter.
What is the due date after IUI?
IUI is performed around ovulation, so the due date is about 266 days after the IUI date (or 280 days after the LMP).
When will my first IVF ultrasound be?
Most clinics scan at 6–7 weeks of pregnancy (about 3–4 weeks after a Day-5 transfer) to confirm the sac location and heartbeat.

⚠️ Official Medical Disclaimer

This calculator is for informational and educational purposes only. It produces mathematical estimates based on published clinical literature (ACOG, ASRM, ESHRE, NICE, WHO, NEJM) and is not a medical diagnosis, treatment plan, or method of contraception.

Every body and every treatment cycle is different. Always discuss your results with a qualified OB-GYN, reproductive endocrinologist, or fertility specialist before making any medical decision. Seek urgent care for heavy bleeding, severe one-sided pain, fainting, or fever.

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