A Randomized Trial Comparing the Live Birth Rate of Immediate Versus Delayed FET Following a Freeze-all Strategy

Study Overview
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Brief Summary
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This randomized trial we aim to compare the live birth rate of immediate versus delayed FET replacing a single blastocyst in the first FET of the first stimulated IVF cycle following. The hypothesis is that the live birth rate of the immediate FET is higher than the delayed FET replacing a single blastocyst in the first FET of the first stimulated IVF cycle following a freeze-all strategy. Women will undergo IVF/ICSI in the centre as clinically indicated. Standard ovarian stimulation with gonadotrophins in a Gonadotrophin releasing hormone (GnRH) antagonist protocol will be employed. Hormone replacement treatment (HRT) will be used in subsequent FET cycles. On Day 3 of the menstrual cycle, we will measure the anxiety levels using the Chinese State-Trait Anxiety Inventory and serum E2, cortisol levels will be checked on the same day. Recruited women having the first FET cycle following a freeze all strategy will be randomly assigned on the day of blastocyst(s) freezing according to a computer-generated randomization list into one of the following two groups.

Official Title
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A Randomized Trial Comparing the Live Birth Rate of Immediate Versus Delayed Frozen Embryo Transfer (FET) Replacing a Single Blastocyst in the First FET of the First Stimulated IVF Cycle Following a Freeze-all Strategy

Conditions
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IVF, Frozen Embryo Transfer

Intervention / Treatment
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* Procedure: Immediate FET
* Procedure: Delayed FET


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Women aged 20-40 years at the time of IVF/ICSI Women undergoing their first FET of the first IVF cycle following a freeze-all strategy Undergoing IVF with GnRH antagonist At least one frozen blastocyst Exclusion Criteria: Severe ovarian hyperstimulation syndrome during the first IVF/ICSI cycle Preimplantation genetic testing Use of donor oocytes Presence of untreated hydrosalpinx or endometrial polyp on scanning during ovarian stimulation

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Immediate FET group<br>FET will be performed in the first menstrual cycle following the stimulated IVF cycle | Procedure: Immediate FET<br>* FET is performed in the first menstrual cycle following the stimulated IVF cycle<br>|
| Other: Delayed FET group<br>FET will be performed in the second menstrual cycle following the stimulated IVF cycle | Procedure: Delayed FET<br>* FET is performed in the second menstrual cycle following the stimulated IVF cycle<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| live birth | deliveries ≥22 weeks gestation with heartbeat and breath | 1 year after FET | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| positive hCG | serum β-hCG ≥10 mIU/mL | 2 weeks after FET | 
| clinical pregnancy | presence of intrauterine gestational sac by trans-vaginal ultrasound at 6 gestational weeks. | 6 weeks' gestation | 
| ongoing pregnancy | a viable pregnancy beyond 12 weeks' gestation | 12 weeks' gestation | 
| implantation rate | the number of gestational sacs per blastocyst transferred | 6 weeks' gestation | 
| miscarriage | a clinically recognized pregnancy loss before the 22 weeks of pregnancy | 1 year after FET | 
| multiple pregnancy | more than one intrauterine sacs on scanning | multiple pregnancy beyond gestation 12 weeks | 
| ectopic pregnancy | pregnancy outside the uterine cavity | ectopic pregnancy during 12 weeks gestation | 
| birthweight of newborns | the birth weight of newborns | 1 year after FET |