The number of autologous, vitrified mature oocytes needed to obtain three euploid blastocysts increases with age.
Level 3 - non-randomized controlled study
Retrospective multicenter cohort study
PubMed 40280226 · doi:10.1016/j.fertnstert.2025.04.023
What was done
This retrospective multicenter cohort study analyzed 1,041 oocyte thaw cycles from 986 patients who warmed autologous vitrified oocytes for in vitro fertilization between 2011 and October 2023. Patients were stratified by age at the time of vitrification to evaluate the number of mature (metaphase II [MII]) oocytes required to obtain at least three euploid blastocysts and to assess expected live births per thawed MII oocyte.
What was found
Patients aged <35 years at vitrification required a mean of 15 MII oocytes to achieve at least three euploid blastocysts. The required number of MII oocytes doubled in patients aged ≥38 years and tripled in patients aged >40 years. Expected live births per thawed MII oocyte were 0.13 for women <35 years versus 0.04 for women >40 years at vitrification. Patients aged 35–40 years utilized preimplantation genetic testing more frequently than those <35 or >40 years. Age at vitrification was more predictive of expected live birth outcomes than the specific clinical indication for cryopreservation.
Why it matters
These findings provide concrete, age-stratified targets for fertility preservation counseling, demonstrating that patients banking eggs at or after age 38 will generally require multiple retrieval cycles to accumulate enough mature oocytes for a high cumulative live birth probability.
Limits
The study is limited by its retrospective design and potential selection bias regarding which patients chose to thaw oocytes and pursue preimplantation genetic testing. The primary endpoint relied on achieving three euploid blastocysts as a surrogate for live birth rather than complete per-transfer pregnancy follow-up for every generated embryo. Clinical protocols and laboratory vitrification techniques may have also shifted across the 12-year study window.
Cited by
- supports In IVF, producing one viable embryo requires approximately 3 eggs at age 25 to 28, but requires roughly 10 to 15 eggs at age 40.