Clinical trial NCT05898178: Embryo Culture Under Constant 5% vs Gradient 8%, 5%, 2% Oxygen Concentration
Official title: The Effect of Constant 5% Versus Gradient 8%, 5%, 2% Oxygen Concentration on the Development of Sibling Human Embryos in Vitro
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Embryonic Development
Embryo Morphokinetics
Embryo Morphometry
Keywords: Embryo culture, reduced oxygen, time-lapse, blastocyst
Lead sponsor: University Medical Centre Maribor
Sponsor class: OTHER
First posted: 2023-06-12
Enrollment: 44
Sex: FEMALE
Minimum age (years): 18
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Intervention model description: 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).
Primary purpose: OTHER

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.

Detailed description: Several studies have shown that embryonic morphological parameters improved when the oxygen concentration in embryo culture was reduced from 20% to 5%. Early mammalian embryos developed faster, had shorter cell cycles, a higher blastocyst formation rate and a better integrity of the inner cell mass (ICM) compared to embryos cultured at 20% oxygen concentration.

Recent studies have shown that the oxygen concentration in the female reproductive tract is not static. In the fallopian tubes of higher mammals it is at around 8%, while in the uterus, at the time of embryo implantation, the oxygen concentration is almost anoxic (2%).

Mimicking such physiological conditions that better reflect the in vivo environment in the human reproductive tract is the goal of assisted reproductive technology (ART).

The aim of this study is to assess whether changing the static 5% oxygen during five days of in vitro embryo culture to the gradient of oxygen, 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, better reflects conditions found within the human reproductive tract and improves embryo developmental characteristics.

Eligibility criteria: Inclusion Criteria:

* 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.

Exclusion Criteria:

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

Primary outcomes:
measure: Proportion of Inseminated Oocytes Developed to the Morphologically Optimal Blastocysts on Day 5
timeFrame: Embryos will be annotated on day 5 post insemination (at 8:00 am).
Secondary outcomes:
measure: Measured Times From Insemination to Different Embryonic Stages Reached
timeFrame: Morphokinetic timings were recorded continuously (every 5 minutes) throughout embryo culture, up to 124 hours (Day 5) post-insemination.
measure: Blastocyst and Inner Cell Mass (ICM) Surface Area Measurement on Day 5
timeFrame: Fix time (116 hours) post insemination
measure: Number of Trophectoderm Cells on Day 5
timeFrame: Fix time (116 hours) post insemination.
measure: Incidence of Atypical Embryo Cleavages
timeFrame: Continuously (a picture will be taken every 5 minutes) during 5 days of embryo culture.
Other outcomes:
Locations:
city: Maribor
country: Slovenia
facility: University Medical Centre Maribor
Study officials:
References: