Objective: To evaluate patient characteristics and fresh in vitro fertilization (IVF) cycle parameters that influence success of sibling frozen-thawed embryo transfer (FET) cycles.
Design: Retrospective study.
Setting: Academic infertility practice.
Patient(s): Infertile women undergoing FET cycles using embryos cryopreserved on day 3 after insemination after an initial fresh IVF cycle.
Intervention(s): 90 FET cycles.
Main outcome measure(s): Clinical pregnancy (CP).
Result(s): The likelihood of CP after FET was statistically significantly higher in women who had achieved CP in the preceding fresh IVF cycle (71.4% vs. 40.6%). Multivariable logistic regression analysis confirmed that patients achieving CP after the fresh IVF cycle were more likely to achieve CP after FET (OR 5.5; 95% CI, 1.2-25.3) after adjusting for age, number, and cleavage status of embryos transferred. Additionally, higher serum levels of progesterone on the day of human chorionic gonadotropin administration emerged as predictive of CP after FET at a statistically significant level.
Conclusion(s): The outcome of the fresh embryo transfer cycle is the foremost predictor of CP after FET of the sibling embryos. The relationship between serum progesterone on the day of human chorionic gonadotropin administration in the fresh cycle and the outcome of subsequent FET is noteworthy and merits further investigation.