The Impact of Assisted Hatching on Pregnancy Outcomes After Vitrified-Warmed Embryo Transfer in Advanced-age Patients

The Impact of Laser-Assisted Hatching on Pregnancy Outcomes After Vitrified-Warmed Embryo Transfer in Advanced-age Patients: A Randomized Controlled Trial

The goal of this clinical trial is to evaluate the effect of laser assisted hatching (LAH) on pregnancy outcomes, with live birth rate as the primary outcome, in advanced age infertile women aged ≥35 years who are undergoing non-donor IVF/ICSI cycles and planning vitrified-warmed embryo transfer. It also aims to monitor the safety of LAH and assess various secondary pregnancy and neonatal outcomes. The main questions it aims to answer are:

Does laser assisted hatching improve the live birth rate in advanced age women undergoing vitrified-warmed embryo transfer? Does laser assisted hatching affect secondary outcomes including implantation rate, biochemical pregnancy rate, clinical pregnancy rate, ectopic pregnancy rate, ongoing pregnancy rate, miscarriage rate, multiple pregnancy rate, preterm birth rate, and rates of obstetric and neonatal complications as well as congenital anomalies? Researchers will compare the Laser Assisted Hatching (LAH) Group to the Control Group (without LAH) to see if LAH can improve pregnancy outcomes in the study population.

Participants will:

• Be randomly assigned to either the LAH Group or the Control Group at a 1:1 ratio, stratified by age (<40 years/≥40 years) and embryo stage (cleavage stage/blastocyst) using stratified block randomization.
• Undergo the first or second frozen-thawed embryo transfer cycle, with transferred embryos meeting the quality criteria (cleavage-stage embryos: Grade I, Grade II, or CP and above; blastocysts: 4BC/CB and above).
• Receive embryo vitrification and warming after routine fertilization and culture; LAH Group will undergo LAH (thinning zona pellucida for cleavage-stage embryos, removing 1/4-1/3 of zona pellucida circumference for blastocysts) in G2 medium after embryo thawing, while Control Group will not receive assisted hatching.
• Have endometrial preparation by natural, ovulatory, or hormone replacement cycles as appropriate, and 1-2 viable embryos will be transferred under ultrasound guidance within 3 hours after thawing, followed by routine luteal support after transfer.
• Complete follow-up at multiple time points: 12-15 days after embryo transfer (serum β-hCG test), 28 days after embryo transfer (transvaginal ultrasound), 12 weeks of gestation (ultrasound), 28 weeks of gestation (ultrasound), and 1 month after delivery (collection of delivery and neonatal information).
• Provide demographic, clinical, and embryological baseline data, as well as various outcome data during the study period.
• Undergo regular monitoring of vital signs, laboratory test results, and adverse events, with key prevention and control of specific risks related to LAH such as embryo damage and multiple pregnancy.

Study Overview

• Status: Not yet recruiting
• Conditions: Advanced Age; Assisted Hatching
• Intervention / Treatment: Procedure: Laser assisted hatching

• Study Type: Interventional
• Enrollment (Estimated): 916
• 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: Female age ≥ 35 years
• 2: First or second vitrified-warmed embryo transfer cycle
• 3: Quality of embryos for transfer meeting the criteria: Grade I, II, CP or above (cleavage-stage embryos); Grade 4BC/CB or above (blastocysts)
• 4: Provide written informed consent

Exclusion Criteria:

• 1: Use of donor oocytes or sperm, or planned preimplantation genetic testing (PGT)
• 2: Severe immune or chromosomal abnormalities
• 3: Uterine cavity abnormalities (i.e., adenomyosis, submucous uterine fibroids, hydrosalpinx, uterine septum, and endometrial polyps)
• 4: Embryos with an abnormal zona pellucida
• 5: Complicated with severe underlying diseases (e.g., uncontrolled hypertension/diabetes mellitus, active malignant tumors)
• 6: A history of recurrent implantation failure (≥2 cycles) or recurrent miscarriage (≥2 episodes)

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: Laser Assisted Hatching (LAH) Group; Laser assisted hatching will be performed on vitrified-warmed embryos prior to embryo transfer according to standard laboratory procedures. For cleavage-stage embryos, the zona pellucida will be thinned; for blastocysts, 1/4-1/3 of the zona pellucida circumference will be removed, and the operation will be performed in G2 medium after embryo thawing.	Procedure: Laser assisted hatching; Laser assisted hatching will be performed on vitrified-warmed embryos prior to embryo transfer according to standard laboratory procedures. For cleavage-stage embryos, the zona pellucida will be thinned; for blastocysts, 1/4-1/3 of the zona pellucida circumference will be removed, and the operation will be performed in G2 medium after embryo thawing.
No Intervention: Control Group (No AH); Embryos will undergo routine vitrification-warming and preparation without assisted hatching prior to transfer, and will be transferred within 3 hours after thawing.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Live birth rate	Live birth rate is defined as the proportion of all enrolled participants who achieved a live birth, defined as the delivery of a live infant at ≥28 weeks of gestation with any signs of life (e.g., heartbeat, respiration).	From enrollment to the delivery (≥28 weeks of gestation)

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
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 12 days (blastocyst), 14 days (D3), or 15 days (D2) after embryo transfer
Ectopic pregnancy rate	The proportion of participants enrolled in the study who experienced an ectopic pregnancy, defined as the detection of an extrauterine gestational sac (including heterotopic pregnancy) via ultrasound examination after embryo transfer.	From enrollment to 28 days after embryo transfer
Neonatal complication rate	The proportion of participants who achieved a live birth and delivered a newborn with neonatal complications.	From enrollment to 1 month after delivery
Macrosomia rate	The proportion of participants who achieved a live birth and delivered a newborn with a birth weight of ≥4000g.	From enrollment to the delivery
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
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
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
Multiple pregnancy rate	The proportion of participants enrolled in the study diagnosed with multiple pregnancy, defined as the confirmation of ≥2 intrauterine gestational sacs via ultrasound examination 28 days after embryo transfer.	From enrollment to 28 days 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 16, 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: March 18, 2026
• First Posted (Actual): March 24, 2026

Study Record Updates

• Last Update Posted (Actual): March 24, 2026
• Last Update Submitted That Met QC Criteria: March 18, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Infertility; Frozen embryo transfer; Advanced maternal age; IVF/ICSI; Live birth; Laser-Assisted hatching;; Vitrified-warmed embryo transfer
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Infertility
• Other Study ID Numbers: SH9H-2026-T42-2

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