Live birth rates after different endometrial preparation methods in frozen cleavage-stage embryo transfer cycles: a randomized controlled trial

Purpose: This study aimed to compare the clinical outcomes in different endometrial preparation methods prior to frozen embryo transfer (FET) in women with normal menstrual cycles. Methods: A total of 471 eligible patients were randomly allocated into four groups of endometrial preparation prior to FET: natural cycle with spontaneous ovulation (n = 120), natural cycle with human chorionic gonadotropin (hCG) for ovulation induction (n = 117), hormone replacement cycle (HRC) (n = 113) and HRC with pre-treatment with GnRH-a (n = 121). Natural cycle with hCG also received hCG in luteal phase. The primary outcome was live birth rate. The secondary outcomes included implantation, biochemical and clinical pregnancy, ongoing pregnancy, and late miscarriage rates. Data analysis included t test, ANOVA and χ². Results: There were no statistically significant differences in the mean age (p = 0.31), duration (p = 0.43) and cause of infertility (p = 0.77) and the number (p = 0.33) and quality (p = 0.21) of embryos transferred between the groups. No significant differences regarding the implantation rates per embryo transfer (p = 0.97) and biochemical pregnancy rates (p = 0.90) were observed between the groups. The rates of clinical pregnancy were 34.2%, 32.5%, 31% and 36.4% in the natural cycle, natural with hCG, HRC and HRC with GnRH-a groups, respectively (p = 0.83). Ongoing pregnancy (p = 0.89) and miscarriage (p = 0.33) rates were comparable between groups. The rate of live birth was 30.8% in the natural group, 30% in the natural with hCG, 27.4% in the HRC and 31.4% in the HRC with GnRH-a groups (p = 0.91). Conclusion: Four different types of endometrial preparation methods for FET cycles appear to be equally effective in terms of implantation, pregnancy, miscarriage and live birth rates in women with normal menstrual cycles. Clinical Trial Registration Number: NCT02251925.