Data will be analyzed using the intention-to-treat principle and a P value of 0.05 or less will be considered significant. Continuous variables will be analyzed with the unpaired t test and general linear model for repeated measures analysis with Bonferroni test for the post-hoc analysis as required. For categorical variables, the Pearson chi-square and Fisher's exact tests will be used. Cumulative pregnancy rate, our primary end-point, will be calculated by the Kaplan-Maier method, and the differences between the two groups will be assessed with the log-rank test. Cox proportional-hazards model will be used to calculate the hazard ratio for new pregnancy in both groups.