Due dates after IVF
With in vitro fertilization, the date of fertilization is known, so the due date can be calculated precisely from the embryo transfer date and the age of the embryo on that day. To use the same convention as natural pregnancies, the calculator converts the transfer into an equivalent first day of the last period: 14 days before fertilization.
The formulas
- Equivalent last period = transfer date − embryo age (days) − 14
- Due date = equivalent last period + 280 days
- Day-5 blastocyst: due date = transfer + 261 days
- Day-3 embryo: due date = transfer + 263 days
For a frozen embryo transfer, use the embryo’s age when it was frozen, not the time spent in storage.
Worked example
A day-5 blastocyst is transferred on October 14, 2026.
- Equivalent last period: October 14 − 5 − 14 days = September 25, 2026.
- Due date: September 25 + 280 days = Friday, July 2, 2027.
- On November 3, 2026, you are 5 weeks and 4 days pregnant.
- The beta hCG blood test is usually around October 23, 9 days after the transfer.
Timeline after the transfer
| Day after a day-5 transfer | What happens |
|---|---|
| 1 to 2 | the blastocyst hatches and attaches |
| 3 to 5 | implantation |
| 6 to 9 | hCG rises into the detectable range |
| 9 to 11 | blood test at the clinic |
| about 3 weeks | first ultrasound, 5 to 6 weeks of pregnancy |
Pregnancy weeks after IVF
On the day of a day-5 transfer, the pregnancy is already counted as 2 weeks and 5 days, and on the day of the blood test as about 4 weeks. These numbers can feel surprising, but they let doctors use the same charts and milestones for every pregnancy.
Waiting for the test
Home tests taken before the clinic’s blood test can mislead: too early, they may be negative; after an hCG trigger shot, they may show a false positive from the injection itself, typically for up to 10 to 14 days. Follow your clinic’s instructions and wait for the blood test when you can.
A note on medical advice
This calculator gives estimates based on averages. It does not replace advice from your doctor, midwife or health care provider, who will date your pregnancy and follow it with exams and ultrasounds.