Related Experiment Video
Updated: Apr 16, 2026
Minimally Invasive Embryo Transfer and Embryo Vitrification at the Optimal Embryo Stage in Rabbit Model
Published on: May 16, 2019
Freeze-all policy: fresh vs. frozen-thawed embryo transfer
Matheus Roque1, Marcello Valle1, Fernando Guimarães1
1ORIGEN, Center for Reproductive Medicine, Rio de Janeiro, Brazil.
Objective:
To compare in vitro fertilization (IVF) outcomes between fresh embryo transfer (ET) and frozen-thawed ET (the "freeze-all" policy), with fresh ET performed only in cases without progesterone (P) elevation.
Design:
Prospective, observational, cohort study.
Setting:
Private IVF center.
Patient(S):
A total of 530 patients submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone-antagonist protocol, and cleavage-stage, day-3 ET.
Intervention(S):
None.
Main Outcome Measure(S):
Ongoing pregnancy rates.
Result(S):
A total of 530 cycles were included in the analysis: 351 in the fresh ET group (when P levels were ≤1.5 ng/mL on the trigger day); and 179 cycles in the freeze-all group (ET performed after endometrial priming with estradiol valerate, at 6 mg/d, taken orally). For the fresh ET group vs. the freeze-all group, respectively, the implantation rate was 19.9% and 26.5%; clinical pregnancy rate was 35.9% and 46.4%; and ongoing pregnancy rate was 31.1% and 39.7%.
Conclusion(S):
The IVF outcomes were significantly better in the group using the freeze-all policy, compared with the group using fresh ET. These results suggest that even in a select group of patients that underwent fresh ET (P levels ≤1.5 ng/mL), endometrial receptivity may have been impaired by COS, and outcomes may be improved by using the freeze-all policy.
