SART and ASRM transfer dating standards
The American Society for Reproductive Medicine (ASRM) and SART standardize gestational age calculations based on embryo development stage.
For a Day 5 blastocyst, gestational age at transfer is 2 weeks 5 days (19 days). For a Day 3 transfer, gestational age is 2 weeks 3 days (17 days).
After initial quantitative hCG monitoring, US patients typically graduate from reproductive endocrinology care to general OB-GYN care at 8 to 10 weeks of gestation.
Worked example: US FET protocol
A patient has a euploid blastocyst transfer on September 1st. Adding 261 days establishes an estimated due date of May 20th.
At transfer, the equivalent LMP date is August 13th. The first formal OB-GYN intake visit is scheduled for late October.
US IVF inputs
Transfer Type
Day 5 blastocyst, Day 3 embryo, or Day 6 blastocyst.
CALCULATOR QUESTIONS
SART & ASRM IVF due date calculator questions
Why does a Day 6 blastocyst have the same calculation as Day 5?
A Day 6 blastocyst is transferred at the same developmental stage (blastocyst) as a Day 5 embryo; it simply reached that stage one day later. Clinicians calculate gestational age as 19 or 20 days.
When can I take a home pregnancy test after embryo transfer?
Taking a test before 7 to 9 days post-transfer (7–9 DPT) can produce false negatives due to low urine hCG or false positives if an hCG trigger shot was administered prior to retrieval.