IVF Due Date Calculator
Calculate your estimated due date from a fresh or frozen embryo transfer. Supports Day 3 and Day 5 blastocyst transfers.
How Is an IVF Due Date Calculated?
An IVF due date is calculated based on 266 days from the date of egg retrieval (fertilization). Since the exact fertilization date is known in IVF, this method is more precise than the standard Naegele's rule used for natural pregnancies.
For a Day 3 embryo transfer, the calculator subtracts 3 days from the transfer date to estimate the fertilization date, then adds 266 days. For a Day 5 blastocyst transfer, it subtracts 5 days. If the egg retrieval date is provided directly (for fresh transfers), the calculator uses that date plus 266 days.
Frozen embryo transfers (FET) use the same logic—the embryo age at freezing (Day 3 or Day 5) is subtracted from the transfer date to estimate the original fertilization date.
Day 3 vs. Day 5 Transfer
A Day 3 transfer places the embryo in the uterus at the cleavage stage, while a Day 5 transfer uses a blastocyst—a more developed embryo. The due date calculation differs by 2 days because the blastocyst has been developing 2 days longer outside the body.
Frequently Asked Questions
- How is an IVF due date calculated?
- An IVF due date is based on 266 days from the fertilization (egg retrieval) date. For Day 3 transfers, subtract 3 from the transfer date to find the fertilization date, then add 266 days. For Day 5 transfers, subtract 5 days instead.
- What is the difference between Day 3 and Day 5 transfer due dates?
- The due dates differ by 2 days. A Day 5 blastocyst has developed 2 days longer than a Day 3 embryo, so the due date for a Day 5 transfer is 2 days earlier when calculated from the same transfer date.
- Is an IVF due date the same as a natural pregnancy due date?
- The gestational length is the same (approximately 40 weeks from the last menstrual period equivalent), but IVF due dates are more precise because the exact fertilization date is known, unlike natural conception where the date is estimated.
- What if my embryo transfer date is in the future?
- You can still calculate an estimated due date based on a planned transfer date. The calculator will show a note that the due date is based on a future transfer and may change if the transfer date shifts.
- How accurate is an IVF due date calculator?
- IVF due date calculators are among the most accurate because the fertilization date is precisely known. However, only about 5% of babies are born on their exact due date. Most births occur within 2 weeks before or after the estimated due date.