Statistical analysis Baseline characteristics of the patients were expressed as mean ±standard deviation or frequencies and proportion (%). The pregnancy and implantation rates were calculated based on the cases of pregnancy and number of gestational sacs. A Chi-Square Test was used to compare the implantation and conception proportions between two groups. The Statistics Package for Social Science (SPSS 13.0; SPSS Inc.) was used for statistical analyses. Statistical significance was set at P<0.05.