FET-LET-2x2: A Randomized Open-Label 2×2 Factorial Trial Comparing Clinical Pregnancy Rates After Frozen Embryo Transfer in True and Modified Natural Cycles With and Without Aromatase Inhibitors
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 入组人数
- 120
- 试验地点
- 1
- 主要终点
- Clinical Pregnancy Rate
研究概览
简要总结
The goal of this clinical trial is to learn whether different natural approaches to preparing the uterus for frozen embryo transfer (FET) can improve pregnancy success in women undergoing in vitro fertilization (IVF) treatment.
The main questions it aims to answer are:
- Is a completely natural menstrual cycle more successful than a natural cycle in which ovulation is triggered with medication when preparing for frozen embryo transfer?
- Does taking a medication called letrozole at the beginning of the cycle improve pregnancy success compared to not taking it?
Researchers will compare four different approaches to see which one results in the highest chance of achieving a clinical pregnancy, confirmed by ultrasound.
Participants will:
- Be randomly assigned to one of four groups
- Undergo monitoring with ultrasound and blood hormone tests during their menstrual cycle
- In some groups, take letrozole tablets for a few days early in the cycle
- In some groups, receive a hormone injection to help control the timing of ovulation
- Undergo frozen embryo transfer at the appropriate time
- Receive standard hormonal support after embryo transfer
- Researchers will compare four different approaches to see which one results in the highest chance of achieving a clinical pregnancy, confirmed by ultrasound.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Factorial
- 主要目的
- Treatment
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 40 Years（Adult）
- 性别
- Female
- 接受健康志愿者
- 否
入选标准
- •Women aged 18 to 40 years
- •Regular menstrual cycles (26-35 days)
- •Scheduled for frozen embryo transfer (FET) in a natural menstrual cycle
- •Normal gynecological ultrasound findings without clinically significant uterine abnormalities
- •Ability to provide written informed consent
排除标准
- •Use of preimplantation genetic testing (PGT) for the transferred embryo
- •Use of donor oocytes
- •Inadequate embryo survival after thawing, defined as loss of viability in more than 50% of blastomeres
- •Irregular menstrual cycles
- •Presence of clinically significant uterine abnormalities detected by ultrasound
- •Inability or unwillingness to provide written informed consent
研究组 & 干预措施
True Natural Cycle Without Letrozole
Participants undergo frozen embryo transfer in a true natural menstrual cycle without the use of either an aromatase inhibitor or ovulation trigger medication. Ovulation is monitored by ultrasound and serum hormone levels. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated on the day of ultrasound-confirmed ovulation and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Progesterone (Drug)
True Natural Cycle With Letrozole
Participants undergo frozen embryo transfer (FET) in a true natural menstrual cycle with administration of the aromatase inhibitor letrozole (2.5 mg twice daily) from cycle days 3-7. Ovulation is monitored by ultrasound and serum hormone levels. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated on the day of ultrasound-confirmed ovulation and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Letrozole (Aromatase Inhibitors) (Drug)
True Natural Cycle With Letrozole
Participants undergo frozen embryo transfer (FET) in a true natural menstrual cycle with administration of the aromatase inhibitor letrozole (2.5 mg twice daily) from cycle days 3-7. Ovulation is monitored by ultrasound and serum hormone levels. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated on the day of ultrasound-confirmed ovulation and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Progesterone (Drug)
Modified Natural Cycle Without Letrozole
Participants undergo frozen embryo transfer in a modified natural menstrual cycle without the use of an aromatase inhibitor. When the dominant follicle reaches ≥17 mm and endometrial thickness is ≥7 mm, and after exclusion of a spontaneous LH surge by serum measurement, ovulation is triggered with recombinant human chorionic gonadotropin (hCG) 250 mcg. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated 2 days after ovulation trigger and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Choriogonadotropin alpha (r-hCG) (Drug)
Modified Natural Cycle Without Letrozole
Participants undergo frozen embryo transfer in a modified natural menstrual cycle without the use of an aromatase inhibitor. When the dominant follicle reaches ≥17 mm and endometrial thickness is ≥7 mm, and after exclusion of a spontaneous LH surge by serum measurement, ovulation is triggered with recombinant human chorionic gonadotropin (hCG) 250 mcg. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated 2 days after ovulation trigger and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Progesterone (Drug)
Modified Natural Cycle With Letrozole
Participants undergo frozen embryo transfer (FET) in a modified natural menstrual cycle with administration of letrozole (2.5 mg twice daily) from cycle days 3-7. Ultrasound monitoring begins between cycle days 8-10. When the dominant follicle reaches ≥17 mm and endometrial thickness is ≥7 mm, and after exclusion of a spontaneous LH surge by serum LH measurement, ovulation is triggered with recombinant human chorionic gonadotropin (hCG) 250 mcg. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated 2 days after ovulation trigger and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Letrozole (Aromatase Inhibitors) (Drug)
Modified Natural Cycle With Letrozole
Participants undergo frozen embryo transfer (FET) in a modified natural menstrual cycle with administration of letrozole (2.5 mg twice daily) from cycle days 3-7. Ultrasound monitoring begins between cycle days 8-10. When the dominant follicle reaches ≥17 mm and endometrial thickness is ≥7 mm, and after exclusion of a spontaneous LH surge by serum LH measurement, ovulation is triggered with recombinant human chorionic gonadotropin (hCG) 250 mcg. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated 2 days after ovulation trigger and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Choriogonadotropin alpha (r-hCG) (Drug)
Modified Natural Cycle With Letrozole
Participants undergo frozen embryo transfer (FET) in a modified natural menstrual cycle with administration of letrozole (2.5 mg twice daily) from cycle days 3-7. Ultrasound monitoring begins between cycle days 8-10. When the dominant follicle reaches ≥17 mm and endometrial thickness is ≥7 mm, and after exclusion of a spontaneous LH surge by serum LH measurement, ovulation is triggered with recombinant human chorionic gonadotropin (hCG) 250 mcg. Luteal phase support (vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily) is initiated 2 days after ovulation trigger and continued until 12 weeks of gestation if pregnancy occurs.
干预措施: Progesterone (Drug)
结局指标
主要结局
Clinical Pregnancy Rate
时间窗: Approximately 4-6 weeks after embryo transfer.
Number of pregnancies with an ultrasound-confirmed gestational sac per embryo transfer.
次要结局
- Biochemical Pregnancy Rate(Two weeks after embryo transfer.)
- Implantation Rate(Approximately 4-6 weeks after embryo transfer.)
- Miscarriage Rate(Up to 23 weeks of gestation.)
研究者
Jelena Vuković
teaching assistant
University of Novi Sad