Embryo Culture Under Constant 5% vs Gradient 8%, 5%, 2% Oxygen Concentration

NCT05898178 | Completed Results

• 2 other identifiers: 0120-405/2021/4P3-0327
• Study Type: interventional
• Target: 44
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this study is to investigate the development of human embryos in vitro under two different oxygen concentrations; a static 5% during all five days of culture or under an oxygen gradient, starting with 8% from day-0 to day-3, continuing with 5% on day-3 and following with 2% of oxygen from the end of day-3 to day-5.

Conditions

Embryonic Development; Embryo Morphokinetics; Embryo Morphometry

Keywords

Embryo culture, reduced oxygen, time-lapse, blastocyst

Outcome Measures

Primary Outcomes (1)

• Proportion of Inseminated Oocytes Developed to the Morphologically Optimal Blastocysts on Day 5

  The primary outcome measure will be the proportion of oocytes that will develop to the morphologically optimal day-5 blastocysts, scored 4-5AA according to Gardner criteria. According to the scoring system of Gardner, blastocyst morphology parameters such as the degree of blastocoel expansion (1-5), the morphological appearance of the inner cell mass (ICM) (A, B, C) and the cohesiveness of trophectoderm (TE) (A, B, C) will be measured.

  Embryos will be annotated on day 5 post insemination (at 8:00 am).

Secondary Outcomes (4)

• Measured Times From Insemination to Different Embryonic Stages Reached

  Morphokinetic timings were recorded continuously (every 5 minutes) throughout embryo culture, up to 124 hours (Day 5) post-insemination.

• Blastocyst and Inner Cell Mass (ICM) Surface Area Measurement on Day 5

  Fix time (116 hours) post insemination

• Number of Trophectoderm Cells on Day 5

  Fix time (116 hours) post insemination.

• Incidence of Atypical Embryo Cleavages

  Continuously (a picture will be taken every 5 minutes) during 5 days of embryo culture.

Study Arms (2)

8-5-2% oxygen gradient concentration in the incubator

EXPERIMENTAL

A physiological oxygen gradient concentration in the incubator (8-5-2% O2).

Other: Experimental intervention: 8-5-2% oxygen gradient concentration in the incubator

Control (no intervention)

NO INTERVENTION

Arbitrary cultivation conditions (static 5% 02).

Interventions

Experimental intervention: 8-5-2% oxygen gradient concentration in the incubator OTHER

After oocyte retrieval and insemination, half of a given patient's embryos will be randomly allocated in an incubator set at a gradient of oxygen tension (8-5-2%). The embryos will remain in the incubator until their developmental assessments on day 5.

8-5-2% oxygen gradient concentration in the incubator

Eligibility Criteria

• Age: 18 Years - 35 Years
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age of women between 18 and 35 years.
• Body mass index (BMI) between 18 and 30 kg/m².
• Only patients with ICSI procedure (male factor of infertility, excluding azoospermia) and blastocyst culture.
• Patients from first and second ICSI cycle attempt.
• Gonadotropin hormone-releasing hormone (GnRH) antagonist cycles.

You may not qualify if:

• Presence of endometriosis.
• Previous clinical intervention on ovaries.
• Connected endocrine or metabolic diseases.
• Presence of polycystic ovary syndrome.

Sponsors & Collaborators

• University Medical Centre Maribor: lead

Study Sites (1)

University Medical Centre Maribor

Maribor, 2000, Slovenia

Location

Results Point of Contact

• Title: Borut Kovačič
• Organization: Maribor University Medical Centr

Borut.KOVACIC@ukc-mb.si

Publication Agreements

• PI is Sponsor Employee: Yes

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: INVESTIGATOR
• Masking Details: The cohort of oocyte-cumulus complexes will be divided into either the study or control group by simple randomization. All embryologists involved in the study will be blinded during embryo assessment, measurement, and selection for embryo transfer or vitrification. A code system will be used on the Petri dishes to ensure the embryologists are blinded.
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Prof. Borut Kovačič, PhD

Model Details: 496 sibling oocytes will be randomly allocated for culture either at low oxygen tension (5% O2) (n = 248 oocytes) or a more physiological oxygen gradient (8-5-2% O2) (n = 248 oocytes) for the next 5 days. Immediately after allocation, the oocytes will be inseminated through Intracytoplasmic Sperm Injection (ICSI). The sibling oocytes will always be injected by the same embryologist. Under standard (5%) oxygen concentration, which is currently being used in the cultivating incubators, approximately 15% of all embryos manage to reach a morphological optimal blastocyst, in a patient group younger than 35 years (see Inclusion Criteria). According to the hypothesis that cultivating embryos under a more physiological atmosphere (gradient from 8% to 2%) improves the blastulation rate of embryos to 25%, a sample size of 496 Injected oocytes (248 in each arm), will be needed. Whereby a statistical strength of 80% and α = 0.05 is considered (calculated using power analysis).

Study Record Dates

• First Submitted: April 26, 2023
• First Posted: June 12, 2023
• Study Start: January 1, 2022
• Primary Completion: January 1, 2023
• Study Completion: January 1, 2023
• Last Updated: June 8, 2025
• Results First Posted: June 8, 2025

Record last verified: 2025-06

Locations

SL (1)