How an IVF due date is estimated

For assisted reproduction, the embryo's age and the date it was transferred help establish gestational age. ACOG gives the following examples for an estimated due date. Use the embryo age your clinic gives you, and ask if it is unclear.

  • Day-5 embryo transfer: add 261 calendar days to the transfer date.
  • Day-3 embryo transfer: add 263 calendar days to the transfer date.
  • For a frozen embryo transfer, use the transfer date and the embryo age described by your clinic, not the date the embryo was frozen.

A worked example

A day-5 transfer on January 23, 2027 gives an estimated due date of October 11, 2027. A day-3 transfer on January 21, 2027 gives the same estimate. These examples are calendar calculations, not predictions of a birth date.

  • Check that the day-3 or day-5 option matches your clinic's description.
  • If the result differs from your clinic's due date, ask which date they use and why.

How many weeks pregnant after transfer?

Pregnancy weeks use a dating convention that includes about two weeks before fertilization. Based on ACOG's due-date examples, a day-5 transfer corresponds to 2 weeks and 5 days of gestational age on transfer day; a day-3 transfer corresponds to 2 weeks and 3 days.

  • This is gestational age, not the age of the embryo itself.
  • Once you know the due date your care team uses, the pregnancy-week calculator can show an estimated week and days.

When your team may use a different date

A due date is an estimate. Your fertility team or obstetric clinician uses your treatment records and clinical information to establish the date for your care. Do not change appointment or care decisions based on an online result.

  • Ask your clinic to confirm the transfer date and embryo age.
  • Bring any questions about your dates to your first prenatal visit.