30 Jul 2025 • A study of 32,838 women undergoing their first frozen embryo transfer (FET) after a freeze-all protocol found that embryo cryopreservation duration strongly impacts outcomes.

Key Findings:

• Clinical pregnancy rates (CPR) and live birth rates (LBR) peaked at 64.2% and 54.5%, respectively, within 3 months, then declined, forming an inverted U-shaped pattern.
• In women with estradiol >1000 pg/mL, longer storage within this window improved outcomes, while no timing effect was seen in those with E2 ≤1000 pg/mL.

Optimal FET timing within 3 months—especially in high-E2 patients—enhances success rates and avoids risks of early or prolonged storage.

Source: International Journal of Gynecology & Obstetrics | Read Full Story