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About this tool
Due date from an IVF embryo transfer or egg retrieval date, with the day-3, day-5 and day-6 transfer offsets and a milestone timeline.
After IVF the conception date is known to the day, so the due date is counted from the transfer rather than estimated from a last period: 261 days after a day-5 blastocyst transfer, 263 days after a day-3 transfer, 260 days after a day-6 transfer and 266 days after egg retrieval. This calculator applies those offsets, converts the result into the equivalent LMP date that gestational age is measured from, and lays out the scan and term milestones that follow. It is a dating tool, not medical advice.
Open IVF Due Date Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Uses the known embryo age instead of Naegele's rule, which assumes a 28-day cycle.
Day-3, day-5, day-6 transfers and the egg retrieval date each have their own offset.
NT scan, anomaly scan, viability, early term, full term and post-term dates, all derived from the same anchor.
Add 261 days to the transfer date. A pregnancy runs 266 days from fertilisation, and a day-5 blastocyst has already spent 5 of those days in the lab, so 266 − 5 = 261 days remain from the day of transfer.
Add 263 days to the transfer date — 266 days from fertilisation minus the 3 days the embryo spent developing before transfer. A day-6 blastocyst transfer uses 260 days, and dating from egg retrieval uses the full 266 days.
2 weeks and 5 days for a day-5 transfer, 2 weeks and 3 days for a day-3 transfer. Gestational age is counted from the equivalent last menstrual period, which is 2 weeks before fertilisation, so the embryo's own age is added to that.
Yes, because the conception date is known rather than inferred from a cycle assumed to be 28 days with ovulation on day 14. Even so, only about 4 in 100 babies arrive on the exact due date, and your clinic may still adjust dating after an early scan.
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