Impact of Day 2 Versus Day 3 Fresh Embryo Transfer on Live Birth Rate in Poor-Prognosis Patients

Impact of Day 2 Versus Day 3 Fresh Embryo Transfer on Live Birth Rate in Poor-Prognosis POSEIDON Group 4 Patients: A Single-Center, Parallel-Group, Open-Label Randomized Controlled Trial

This study aimed to compare the efficacy (live birth rate) of fresh embryo transfer on Day 2 versus Day 3 in POSEIDON Group 4 patients, and to determine the optimal timing of embryo transfer for this population. It is a single-center, parallel-group, open-label prospective randomized controlled trial, and outcome assessors are masked. The main questions it aims to answer are:

Is there a significant difference in the live birth rate between Day 2 and Day 3 fresh embryo transfer in patients with POSEIDON Category 4 low prognosis? What are the differences in secondary outcomes (including clinical pregnancy rate, ongoing pregnancy rate, implantation rate, embryo utilization rate, miscarriage rate, incidence of moderate/severe OHSS, and adverse neonatal outcomes) between the two embryo transfer timings, and which timing is safer and more effective for this patient population?

A total of 470 patients meeting the POSEIDON Category 4 criteria will be enrolled and randomly assigned to the Day 2 Fresh Embryo Transfer Group and the Day 3 Fresh Embryo Transfer Group in a 1:1 ratio using stratified block randomization. Researchers will compare the two groups to clarify the difference in live birth rate (primary outcome) and other secondary outcomes, so as to determine the optimal embryo transfer timing.

Participants will:

• Be female patients aged ≥ 35 years with antral follicle count (AFC) < 5 or anti-Müllerian hormone (AMH) < 1.2 ng/mL, undergoing the first or second IVF/ICSI cycle, receiving controlled ovarian hyperstimulation (COH) with the GnRH antagonist protocol, and having ≥ 1 oocyte retrieved (excluding those using donor oocytes/sperm, with uterine cavity abnormalities, or complicated with severe underlying diseases).
• Be randomly assigned to either the Day 2 Fresh Embryo Transfer Group or the Day 3 Fresh Embryo Transfer Group, and receive embryo transfer according to the corresponding group's protocol
• Receive routine luteal support treatment after embryo transfer
• Attend follow-up visits at multiple time points (on the day of transfer, 12-15 days after transfer, 28 days after transfer, during pregnancy, and after delivery) to collect relevant clinical and laboratory data for outcome assessment.
• Undergo safety evaluation throughout the study; the study will adopt intention-to-treat (ITT) as the main statistical method and per-protocol (PP) as the sensitivity analysis, with subgroup analysis by age, AMH level, and number of oocytes retrieved, following ethical norms and data quality control requirements.

Study Overview

• Status: Not yet recruiting
• Conditions: Female Infertility Due to Diminished Ovarian Reserve; POSEIDON Category 4; Low Prognosis in Assisted Reproductive Technology
• Intervention / Treatment: Procedure: Day 2 Fresh Embryo Transfer

• Study Type: Interventional
• Enrollment (Estimated): 470
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: SHUTIAN JIANG, Medical Doctor; Phone Number: 021-23271699; Email: shutiansweet@126.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 1: Meet the definition of POSEIDON Category 4: age ≥ 35 years, with antral follicle count (AFC) < 5 or anti-Müllerian hormone (AMH) < 1.2 ng/mL
• 2: Undergoing first or second IVF/ICSI cycle
• 3: Undergoing controlled ovarian hyperstimulation (COH) using a gonadotropin-releasing hormone (GnRH) antagonist protocol, with at least 1 oocyte retrieved
• 4: Provide written informed consent

Exclusion Criteria:

• 1: Use of donor oocytes/sperm, or planned preimplantation genetic testing (PGT)
• 2: Severe immune or chromosomal abnormalities
• 3: Uterine cavity abnormalities (i.e., submucous fibroids, complete uterine septum, severe intrauterine adhesions, etc.) or untreated, ultrasound-visible hydrosalpinx
• 4: Presence of severe underlying diseases (e.g., uncontrolled hypertension/diabetes mellitus, active malignant tumors)
• 5: History of recurrent implantation failure (≥2 cycles) or recurrent miscarriage (≥2 episodes)
• 6: Progesterone level > 1.5 ng/mL on the day of human chorionic gonadotropin (hCG) trigger

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: D2 Embryo Transfer Group; Embryos will be cultured for 44-48 hours after oocyte retrieval (Day 2), and embryos with ≥ 2 cells, grade II or above, and no multinucleation will be selected for transfer, with 1-2 embryos transferred; routine luteal support treatment will be given after transfer.	Procedure: Day 2 Fresh Embryo Transfer; Embryos will be cultured for 44-48 hours after oocyte retrieval (Day 2), and embryos with ≥ 2 cells, grade II or above, and no multinucleation will be selected for transfer, with 1-2 embryos transferred; routine luteal support treatment will be given after transfer.
No Intervention: D3 Embryo Transfer Group; Embryos will be cultured for 68-72 hours after oocyte retrieval (Day 3), and embryos with ≥ 6 cells, grade II or above, and no multinucleation will be selected for transfer, with 1-2 embryos transferred; routine luteal support treatment will be given after transfer.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Live birth rate	Live birth rate, defined as the delivery of at least one neonate with heartbeat and breathing at ≥ 28 weeks of gestation.	From enrollment to delivery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Ongoing pregnancy rate	The proportion of participants enrolled in the study who experienced an ongoing pregnancy, defined as the confirmation of an intrauterine viable fetus via ultrasound examination at 12 weeks of gestation.	From enrollment to 12 weeks of gestation
Low birth weight rate	The proportion of participants who achieved a live birth and delivered a newborn with a birth weight of less than 2500g.	From enrollment to the delivery
Clinical pregnancy rate	The proportion of participants enrolled in the study who experienced a clinical pregnancy, defined as the confirmation of an intrauterine gestational sac via ultrasound examination 28 days after embryo transfer.	From enrollment to 28 days after embryo transfer
Preterm birth rate	The proportion of participants who achieved a live birth and delivered between 28 and 36⁺⁶ weeks of gestation.	From enrollment to the delivery
Implantation rate	The proportion of all transferred embryos that developed into an intrauterine gestational sac, as confirmed by ultrasound examination 28 days after embryo transfer.	From enrollment to 28 days after embryo transfer
Congenital malformation rate	The proportion of participants who achieved a live birth and delivered a newborn diagnosed with a congenital malformation according to the International Classification of Diseases (ICD-10).	From enrollment to 1 month after delivery
Embryo utilization rate	The proportion of all obtained fertilized embryos (2PN zygotes) that are available for subsequent embryo transfer.	Day 2 or Day 3 after oocyte retrieval
Moderate/severe OHSS incidence rate	The proportion of participants enrolled in the study who developed moderate or severe ovarian hyperstimulation syndrome (OHSS), meeting the criteria of the Royal College of Obstetricians and Gynaecologists (RCOG), between oocyte retrieval and 12 weeks of gestation.	From oocyte retrieval to 12 weeks of gestation
Miscarriage rate	The proportion of participants who experienced a clinical pregnancy and subsequently had a spontaneous pregnancy loss before 28 weeks of gestation.	From enrollment to ≤28 weeks of gestation
Rate of no available embryos	The proportion of participants enrolled in the study who, following ovarian stimulation, oocyte retrieval, and embryo culture, have no embryos available for transfer.	Day 2 or Day 3 after oocyte retrieval
Biochemical pregnancy rate	The proportion of participants enrolled in the study who experienced a biochemical pregnancy, defined as a serum HCG level ≥25 IU/L measured 14 or 15 days after embryo transfer.	From enrollment to 14 days (D3) or 15 days (D2) after embryo transfer

Collaborators and Investigators

• Sponsor: Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University

Study record dates

Study Major Dates

• Study Start (Estimated): March 30, 2026
• Primary Completion (Estimated): September 30, 2027
• Study Completion (Estimated): December 31, 2027

Study Registration Dates

• First Submitted: March 18, 2026
• First Submitted That Met QC Criteria: April 9, 2026
• First Posted (Actual): April 16, 2026

Study Record Updates

• Last Update Posted (Actual): April 16, 2026
• Last Update Submitted That Met QC Criteria: April 9, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: in-vitro fertilization; diminished ovarian reserve; POSEIDON; low prognosis; fresh embryo transfer
• Other Study ID Numbers: SH9H-2026-T107-1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data (IPD), along with the study protocol and statistical analysis plan, will be made publicly available via the National Clinical Research Data Sharing Platform (https://www.ncmc-data.org) within 12 months after study completion. The data will be accessible to qualified researchers in compliance with relevant laws, regulations, and ethical requirements.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No