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NCT Number: NCT04371783

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

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.

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Key information

Conditions

IVF Frozen Embryo Transfer

Age range

20 year–40 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Shanghai JiAi Genetics & IVF Institute

Shanghai, Shanghai Municipality, 200011, China

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Immediate FET

Procedure

FET is performed in the first menstrual cycle following the stimulated IVF cycle

Delayed FET

Procedure

FET is performed in the second menstrual cycle following the stimulated IVF cycle

Primary outcomes

  1. live birth

    Time frame: 1 year after FET

    deliveries ≥22 weeks gestation with heartbeat and breath

Secondary outcomes

  1. positive hCG

    Time frame: 2 weeks after FET

    serum β-hCG ≥10 mIU/mL

  2. clinical pregnancy

    Time frame: 6 weeks' gestation

    presence of intrauterine gestational sac by trans-vaginal ultrasound at 6 gestational weeks.

  3. ongoing pregnancy

    Time frame: 12 weeks' gestation

    a viable pregnancy beyond 12 weeks' gestation

  4. implantation rate

    Time frame: 6 weeks' gestation

    the number of gestational sacs per blastocyst transferred

  5. miscarriage

    Time frame: 1 year after FET

    a clinically recognized pregnancy loss before the 22 weeks of pregnancy

  6. multiple pregnancy

    Time frame: multiple pregnancy beyond gestation 12 weeks

    more than one intrauterine sacs on scanning

  7. ectopic pregnancy

    Time frame: ectopic pregnancy during 12 weeks gestation

    pregnancy outside the uterine cavity

  8. birthweight of newborns

    Time frame: 1 year after FET

    the birth weight of newborns

Sponsors and collaborators

Lead sponsor

ShangHai Ji Ai Genetics & IVF Institute

Other

Registry information

Official study title

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

Acronym: FET

Important dates

Study start
2020
Primary completion
2026
Study completion
2026
First posted
May 1, 2020
Registry last updated
Feb 2, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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