Embryo Culture Under Constant 5% vs Gradient 8%, 5%, 2% Oxygen Concentration
CompletedNAResults postedLast updated 8 June 2025
What this trial tests
NA trial testing Experimental intervention: 8-5-2% oxygen gradient concentration in the incubator in Embryonic Development in 44 participants. Completed in 1 January 2023.
Timeline
1 January 2022
Primary endpoint 1 January 2023
1 January 2023
Quick facts
Lead sponsor
University Medical Centre Maribor
Phase
NA
Status
Completed
Study type
INTERVENTIONAL
Allocation
randomized
Design
parallel
Masking
single
Primary purpose
other
Enrollment
44
Start date
1 January 2022
Primary completion
1 January 2023
Estimated completion
1 January 2023
Sites
1 location across Slovenia
Drugs / interventions tested
Experimental intervention: 8-5-2% oxygen gradient concentration in the incubator
Adults 18 to 35, female only, with Embryonic Development or Embryo Morphokinetics. Patients with the condition only — healthy volunteers not accepted.
Results — posted to ClinicalTrials.gov
Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.
Proportion of Inseminated Oocytes Developed to the Morphologically Optimal Blastocysts on Day 5Primary· Embryos will be annotated on day 5 post insemination (at 8:00 am).
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.
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
27
Control (no Intervention)
38
Measured Times From Insemination to Different Embryonic Stages ReachedSecondary· Morphokinetic timings were recorded continuously (every 5 minutes) throughout embryo culture, up to 124 hours (Day 5) post-insemination.
Using time-lapse software, embryo development videos were reviewed by manually advancing the images frame by frame. Morphokinetic timings were recorded continuously (every 5 minutes) throughout embryo culture, up to 124 hours (Day 5) post-insemination. The following developmental milestones were recorded for each clinically used embryo that reached the blastocyst stage (cryopreserved or transferred):
tPNa - Appearance of individual pronuclei
t2 - Time to 2-cell stage
t3 - Time to 3-cell stage
t4 - Time to 4-cell stage
t5 - Time to 5-cell stage
t6 - Time to 6-cell stage
t7 - Time to 7-ce
tPNa
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
11.4
11 – 12.8
Control (no Intervention)
11.7
11.1 – 12.6
t2
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
25.7
23.6 – 27.7
Control (no Intervention)
25.7
24.9 – 28.5
t3
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
36.6
31.8 – 39.0
Control (no Intervention)
35.1
31.7 – 39.2
t4
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
38.8
35.4 – 41.3
Control (no Intervention)
37.6
36.0 – 41.0
t5
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
49.5
46.1 – 53.0
Control (no Intervention)
48.1
45.0 – 51.3
t6
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
53.2
50.5 – 57.7
Control (no Intervention)
53.1
50.3 – 57.7
t7
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
61.5
55.7 – 67.6
Control (no Intervention)
63.4
56.8 – 67.8
t8
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
69.5
65.8 – 74.6
Control (no Intervention)
71.9
66.4 – 75.1
Blastocyst and Inner Cell Mass (ICM) Surface Area Measurement on Day 5Secondary· Fix time (116 hours) post insemination
Surface measurements of blastocysts and inner cell mass (ICM) will be recorded on time-lapse photos at 116 hours after insemination. The surfaces will be measured in square micrometres using the Primo vision software's measuring tool. An ellipse will be generated around the trophectoderm's outer edge or the inner cell mass. These measurements will exclude the zona pellucida. The measurements will be taken at the focus plane with the largest surface area.
Blastocyst surface area (P, µm²)
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
25994
± 4657
Control (no Intervention)
28198
± 4139
Inner cell mass surface area (ICM, µm²)
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
3695
± 732.5
Control (no Intervention)
3628
± 831.9
Number of Trophectoderm Cells on Day 5Secondary· Fix time (116 hours) post insemination.
At 116 hours following insemination, the number of trophectoderm cells will be counted using time-lapse photos. Images will be focused on the trophectoderm's outermost edge to better determine the boundaries of each individual cell.
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
14.4
± 2.3
Control (no Intervention)
15.3
± 2.8
Incidence of Atypical Embryo CleavagesSecondary· Continuously (a picture will be taken every 5 minutes) during 5 days of embryo culture.
Time-lapse videos for each embryo will be reviewed for atypical cleavage features, such as; pseudofurrows, direct cleavage, reverse cleavage, multinucleation, irregular chaotic division, cell exclusion and blastocyst collapse, using Primo vision software by manually forwarding the images frame by frame. The frequency of abnormal cleavage patterns will be recorded.
Pseudofurrows
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
36
Control (no Intervention)
49
Direct cleavage
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
25
Control (no Intervention)
30
Reverse cleavage
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
14
Control (no Intervention)
9
Irregular chaotic division
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
21
Control (no Intervention)
15
Blastomere exclusion
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
45
Control (no Intervention)
34
Blastocyst collapse
Group
Value
95% CI
8-5-2% Oxygen Gradient Concentration in the Incubator
55
Control (no Intervention)
67
Sponsor's own description
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.
Publications & conference data
No peer-reviewed publications indexed yet for this trial. Completed trials usually publish results within 12-18 months.
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Sponsor: as reported to ClinicalTrials.gov by University Medical Centre Maribor
Last refreshed: 8 June 2025
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