IVF Due Date Calculator
IVF pregnancies have a precisely known conception date, making due-date estimation more accurate than natural cycles. This calculator uses the embryo transfer date and embryo age (Day 3 or Day 5) to compute your estimated due date (EDD), current gestational age, and key prenatal milestones — no LMP guesswork required.
When to use this calculator
- Calculating EDD after a fresh Day-3 or Day-5 embryo transfer
- Calculating EDD after a frozen embryo transfer (FET) with Day-3 or Day-5 embryos
- Tracking gestational age week-by-week after IVF
- Planning first trimester screening and anatomy scan appointments
- Sharing a reliable due date with your OB or midwife
- Comparing IVF due date with a natural-cycle estimate
How it works
2 min readWhat is an IVF due date?
An IVF due date is the estimated delivery date calculated from the embryo transfer date plus the embryo's age in days. Day-5 blastocyst transfers add 261 days; Day-3 transfers add 263 days. This method provides more precise dating than natural conception because the exact fertilization timing is known.
How IVF Due Dates Are Calculated
In natural conception, gestational age is counted from the Last Menstrual Period (LMP), which is approximately 2 weeks before ovulation. A full-term pregnancy is 280 days (40 weeks) from LMP.
In IVF, the retrieval and fertilization dates are known. Embryo age at transfer is counted from the day of egg retrieval (Day 0). The formula back-calculates an equivalent LMP, then adds 280 days.
// Day-3 fresh transfer
LMP equivalent = Transfer Date − 3 days − 14 days = Transfer Date − 17 days
EDD = LMP equivalent + 280 days = Transfer Date + 263 days
// Day-5 blastocyst fresh transfer
LMP equivalent = Transfer Date − 5 days − 14 days = Transfer Date − 19 days
EDD = LMP equivalent + 280 days = Transfer Date + 261 daysFor frozen embryo transfers (FET), the embryo was already cultured to Day 3 or Day 5 before freezing, so the same offset applies. The transfer date is used identically — the freeze/thaw process does not add gestational age.
Gestational Age Milestones
Gestational age (GA) is always counted from the LMP equivalent:
| Milestone | GA | Days from LMP equiv |
|---|---|---|
| End of 1st Trimester | 12w 0d | 84 days |
| Anatomy Scan (mid-pregnancy) | 20w 0d | 140 days |
| Start of 3rd Trimester | 28w 0d | 196 days |
| Full Term begins | 39w 0d | 273 days |
| EDD | 40w 0d | 280 days |
Worked Example
Limitations
Frequently asked questions
Is IVF due date calculation more accurate than natural pregnancy?
Yes. Because the fertilization date is precisely known, the LMP-equivalent calculation is exact. Natural-cycle LMP estimates assume a 28-day cycle and 14-day luteal phase, which varies. IVF EDD error is effectively zero from the formula; clinical variability comes from fetal growth, not date math.
Why does a Day-5 transfer use 261 days and Day-3 uses 263 days?
Both formulas target 280 days from the LMP equivalent. A Day-5 embryo is 5 days old, so the LMP equivalent is 19 days before transfer (5 + 14). A Day-3 embryo is 3 days old, so LMP is 17 days before transfer (3 + 14). 280 − 19 = 261; 280 − 17 = 263.
Does a frozen embryo transfer (FET) change the due date calculation?
No. The freeze-thaw process does not add gestational age. The embryo's developmental stage (Day 3 or Day 5) at the time it was originally cultured is what matters. Use the actual transfer date and the embryo's day, exactly as you would for a fresh transfer.
What if my clinic transferred a Day-6 blastocyst?
Day-6 blastocysts are less common but valid. The formula would be: EDD = Transfer Date + 260 days (LMP equivalent = Transfer Date − 20 days). This calculator currently supports Day 3 and Day 5; ask your clinic to confirm the embryo's day if uncertain.
My ultrasound due date differs from this calculator. Which one is correct?
After the first trimester, ultrasound biometry (crown-rump length at 7–13 weeks) is the gold standard. If the discrepancy is ≤5 days, providers typically keep the transfer-based EDD. If it is >7 days, most clinicians adjust to the ultrasound date. Follow your provider's guidance.
Does a donor egg transfer use the donor's retrieval date?
No. For the gestational carrier or recipient, use the recipient's transfer date and the embryo's developmental day. The donor's retrieval date is relevant to embryology records but not to the recipient's gestational age.
When is the first trimester screening typically scheduled?
First trimester combined screening (nuchal translucency ultrasound + blood work) is performed between 11 weeks 0 days and 13 weeks 6 days of gestational age — roughly 77 to 97 days from your LMP equivalent. Use your 12-week milestone as a planning reference point.
What does 'gestational age' mean for an IVF pregnancy?
Gestational age (GA) counts from the LMP equivalent — the theoretical date 2 weeks before fertilization. At a Day-5 transfer, GA is already 2 weeks + 5 days = 19 days (2 weeks, 5 days). So you are already nearly 3 weeks pregnant on the day of transfer, even though conception just occurred.
Is this calculator suitable for ICSI, IUI, or natural IVF?
ICSI (intracytoplasmic sperm injection) is a fertilization technique used within IVF; the transfer date and embryo day still apply. IUI does not produce a known fertilization date, so use an LMP-based calculator instead. Natural-cycle IVF follows the same formula as conventional IVF.