Evaluation of clinical factors influencing pregnancy rate in frozen embryo transfer

Frozen embryo transfer (FET) is one of the most important supplementary procedures in the treatment of infertile couples. While general information concerning the outcome of fresh embryo transfer has been documented, paucity of investigations has addressed the clinical factors influenced on pregnancy rates in FET.

In this study, we performed a retrospective analysis of clinical factors that potentially influence the outcome of FET.

We reviewed the data from 372 women who were subjected to FET registered from April 2009-2011 at the Research and clinical center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Baseline data and pregnancy rate were collected. The data were analyzed statistically using the Kolmogorov-Smirnov, and Mann-Whitney tests.

The clinical pregnancy rate was 57.7 and 29.2% in women <35 years old, and women >35 years old, respectively (p<0.0001). Clinical pregnancy rates in women with FSH <10 IU/ml, and FSH >10 IU/ml were 56.3% and 17.5 %, respectively (p<0.0001). Whereas the other clinical parameters consist of reason of fetus freezing, primary IVF protocol, IVF procedure, endometrial thickness, treatment duration to fetal transfer found to be unrelated to FET outcomes (p>0.05).

Female age and basal FSH level are the most important factors influencing the clinical pregnancy rate following FET.