IVF Due Date Calculator

Add 261 days to your Day 5 embryo transfer date. The formula is EDD = Transfer Date + (266 minus embryo age). Since a Day 5 blastocyst is 5 days old at transfer, you subtract 5 from the 266-day conception-to-birth period: 266 minus 5 equals 261 days. This gives the same result as adding 266 days to the egg retrieval date, because the embryo spent 5 days in the lab between retrieval and transfer.

Add 263 days to your Day 3 transfer date. A Day 3 embryo (cleavage stage) is 3 days post-fertilization at the time of transfer, so EDD = Transfer Date + (266 minus 3) = Transfer Date + 263. Because Day 3 embryos are transferred earlier in development than Day 5 blastocysts, the same egg retrieval date produces a due date 2 days earlier from a Day 3 transfer compared with a Day 5 transfer.

Yes. IVF dating is based on the known fertilization date (egg retrieval), giving an accuracy of plus or minus 2 to 3 days. Natural LMP-based dating assumes ovulation on day 14, which is incorrect for women with irregular cycles and carries a margin of plus or minus 7 days. For this reason, IVF due dates are rarely revised by the first-trimester ultrasound, whereas LMP-based dates are revised approximately 20 to 30 percent of the time.

At the moment of a Day 5 blastocyst transfer you are 19 days gestational age, which equals 2 weeks and 5 days. This is because gestational age counts from the equivalent of day 1 of the last menstrual period, which by convention is 14 days before fertilization (egg retrieval). Add 14 days plus the 5-day embryo age to get 19 gestational days. After the transfer, gestational age increases by 1 day per calendar day.

Yes. For a frozen embryo transfer (FET), enter your transfer date and the embryo stage at the time the embryo was frozen, typically Day 5 or Day 6. The formula is the same as for fresh transfers because the freezing and thawing process does not add to the embryo's biological age. Day 5 FET: add 261 days to transfer date. Day 6 FET: add 260 days to transfer date.

Yes. The due date formula uses the embryo's age at transfer, not whose eggs were used. Enter the embryo transfer date and the embryo stage exactly as you would for a standard IVF cycle. For gestational age purposes, the donor's egg retrieval date is still used as the fertilization reference point, which is already built into the embryo stage entered at transfer.

LMP-based dating assumes ovulation at day 14 of a 28-day cycle, but IVF cycles use hormonal stimulation that shifts the timing of egg retrieval relative to any natural cycle. Women with cycles longer or shorter than 28 days would get an incorrect LMP-based date. IVF dating bypasses this issue entirely by anchoring the calculation to the documented egg retrieval date rather than estimating ovulation from the cycle.

Most IVF clinics schedule a viability scan between 6 and 8 gestational weeks, approximately 4 to 6 weeks after a Day 5 embryo transfer. This scan confirms a heartbeat, rules out ectopic pregnancy, and verifies the number of implanted embryos. Your clinic will book this automatically after a positive beta hCG blood test. The 8 to 12 week nuchal translucency scan follows, then the anatomy scan at weeks 18 to 20.

Yes, by one day. A Day 6 blastocyst transfer produces an EDD one day later than a Day 5 transfer from the same egg retrieval. EDD for Day 5 transfer = transfer date plus 261 days. EDD for Day 6 transfer = transfer date plus 260 days. From the same retrieval date, both approaches yield the same EDD (retrieval date plus 266). The one-day difference in transfer date is exactly offset by the one-day difference in the addition.

Add 14 days to the number of days since egg retrieval. By convention, gestational age begins 14 days before fertilization (the equivalent of the last menstrual period day in natural cycles). So on the day of egg retrieval you are 14 gestational days old. Each day after retrieval adds one gestational day. For example, 30 days after retrieval you are 44 gestational days, or 6 weeks and 2 days gestational age.

Use the general formula: EDD = Transfer Date + (266 minus embryo age in days). For Day 2 transfers (less common): add 264 days. For Day 4 transfers (morula stage, rare): add 262 days. For Day 7 (rare extended culture): add 259 days. In all cases, the embryo age is the number of days from egg retrieval to the date of the actual transfer, and that number is subtracted from 266.

Very accurate for scheduling purposes. Because IVF uses a known fertilization date, the EDD is reliable to within 2 to 3 days. Appointment timing (beta hCG at 9-11 days after transfer, viability scan at 6-8 weeks, nuchal translucency at 11-13 weeks, anatomy scan at 18-20 weeks) can all be planned from the EDD shown here. However, only your obstetrician or reproductive endocrinologist can confirm dates and interpret scan findings.