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

Study Results

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Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

NA

Total Enrollment

44 participants

Study Classification

INTERVENTIONAL

Study Start Date

2022-01-01

Study Completion Date

2023-01-01

Brief Summary

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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.

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Detailed Description

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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.

Conditions

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Embryonic Development Embryo Morphokinetics Embryo Morphometry

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

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 Study Purpose

OTHER

Blinding Strategy

SINGLE

Investigators

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.

Study Groups

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

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

Group Type EXPERIMENTAL

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

Intervention Type 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.

Control (no intervention)

Arbitrary cultivation conditions (static 5% 02).

Group Type NO_INTERVENTION

No interventions assigned to this group

Interventions

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

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.

Intervention Type OTHER

Eligibility Criteria

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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.

Minimum Eligible Age

18 Years

Maximum Eligible Age

35 Years

Eligible Sex

FEMALE

Accepts Healthy Volunteers

Yes