The IVF Laboratory Environment: Which Factors Actually Influence Embryo Development?

“The IVF laboratory environment is not simply the room in which gametes and embryos are handled. It is the controlled biological environment in which human embryos spend the earliest and most vulnerable stages of development. Temperature, gas composition, pH, oxygen exposure, osmolality, evaporation, air quality, culture media, consumables and laboratory workflow all contribute to that environment.

The 2026 ESHRE recommendations on good practice in IVF laboratories emphasise calibrated monitoring, validated equipment, controlled environmental conditions, appropriate consumables, documented procedures and quality management. The laboratory question is therefore not only whether an incubator reaches its programmed set point, but whether the embryo experiences a stable and reproducible environment throughout the laboratory workflow (ESHRE Good Practice in IVF Lab Working Group, 2026).

What does the IVF laboratory environment actually include?

The IVF laboratory environment consists of both physical conditions and laboratory processes.

Temperature

Human oocytes and embryos are highly temperature-sensitive. Temperature control is therefore required during retrieval, denudation, insemination, ICSI, embryo assessment, biopsy and cryopreservation procedures.

The important variable is not only the incubator display. It is the temperature experienced by the biological material during handling. ESHRE recommends prewarming relevant materials, maintaining appropriate temperature during procedures and minimising fluctuations outside controlled conditions (ESHRE Good Practice in IVF Lab Working Group, 2026).

CO₂ and pH

CO₂ regulates the bicarbonate-buffered culture system and therefore influences culture-medium pH. The appropriate CO₂ concentration depends on the culture medium, incubator configuration, and laboratory validation.

A set point such as 5–6% CO₂ is widely used in human embryo culture, but no single CO₂ concentration represents a universal international standard. The laboratory target is the concentration that maintains the validated physiological pH range of the specific culture system.

Oxygen

Reduced-oxygen culture, commonly around 5% O₂, is widely used in contemporary IVF laboratories. ESHRE recommendations support low oxygen concentration to limit oxidative stress during embryo culture (ESHRE Good Practice in IVF Lab Working Group, 2026).

An important distinction exists between incubator gas composition and the oxygen concentration actually experienced by the embryo.

Kulkarni et al. (2026) demonstrated that oxygen equilibration in embryo-culture droplets is gradual rather than instantaneous. Under their experimental conditions, droplets exposed to atmospheric oxygen required prolonged equilibration after transfer to a 5% O₂ environment. Oil viscosity also influenced oxygen equilibration and reoxygenation kinetics.

These findings do not establish a universal 12-hour equilibration rule for every IVF culture system. They demonstrate that oxygen exposure is a dynamic variable and that unnecessary atmospheric exposure during embryo handling requires control (Kulkarni et al., 2026).

Osmolality and evaporation

Evaporation increases solute concentration and changes culture-medium osmolality. This is particularly relevant when culture dishes remain outside controlled incubation conditions.

Oil overlays reduce evaporation and help stabilise temperature, pH and osmolality, but they do not eliminate evaporation completely. Oil characteristics influence the physical behaviour of culture droplets, while evidence does not establish one oil viscosity as universally superior for clinical outcomes (ESHRE Good Practice in IVF Lab Working Group, 2026).

Laboratories therefore require controlled dish preparation, appropriate oil handling, validated workflows and defined in-use periods.

Which IVF laboratory environment factors matter most?

Not every laboratory variable deserves the same weight. The strongest evidence supports control of variables that directly affect the physical and chemical environment surrounding the embryo.

Culture media

Culture media provide the biochemical environment for embryo development, including energy substrates, amino acids, salts and buffering components.

Current evidence does not establish one universally superior commercial culture medium for all IVF laboratories. The 2026 Cochrane review found limited and inconsistent evidence for clinically meaningful superiority between specific culture-media systems (Laverde et al., 2026).

The practical priority is therefore not selecting a universally ‘best’ medium. It is maintaining a validated culture system with appropriate storage, preparation, equilibration, quality control and documented lot management.

Consumables and oil

Plasticware, pipettes, dishes, tubes and oil are direct components of the embryo’s immediate environment. Their biological safety therefore requires verification.

The 2026 ESHRE recommendations emphasise regulatory compliance, documentation and quality assessment of critical consumables. New critical lots require appropriate validation before clinical use according to laboratory policy and applicable standards (ESHRE Good Practice in IVF Lab Working Group, 2026).

Air quality

The IVF laboratory environment also includes the air surrounding critical procedures. Volatile organic compounds, particulate contamination and microbial contamination represent recognised laboratory-quality risks.

The appropriate response is not to claim that every VOC exposure produces implantation failure. Air quality is better treated as a controlled laboratory risk requiring risk-based assessment and mitigation. ESHRE recommendations include appropriate air filtration, VOC control, and environmental monitoring according to laboratory risk assessment (ESHRE Good Practice in IVF Lab Working Group, 2026).

How does laboratory workflow change the embryo’s environment?

A technically advanced incubator does not compensate for uncontrolled handling.

Every time a dish leaves the incubator, the embryo encounters changes in temperature, gas exposure, humidity, oxygen tension and light exposure. The magnitude and duration of these changes depend on the laboratory workflow.

The 2026 ESHRE recommendations therefore emphasise minimising the time gametes and embryos remain outside controlled conditions, maintaining appropriate temperature and pH, reducing unnecessary light exposure and mechanical stress, and using validated handling procedures (ESHRE Good Practice in IVF Lab Working Group, 2026).

This makes workflow design part of environmental control.

The embryologist is also part of this control system. Timing, consistency, witnessing, pipetting technique, identification procedures, and adherence to validated SOPs influence the reproducibility of laboratory processes.

Quality control (QC) measures whether defined parameters remain within specification. Quality assurance (QA) evaluates whether the broader system is consistently controlled, documented, and capable of producing reproducible laboratory performance.

The Vienna Consensus established laboratory performance indicators and benchmark concepts for ART laboratories, reinforcing the principle that laboratory quality requires systematic measurement rather than reliance on individual observations alone (ESHRE SIG Embryology and Alpha Scientists, 2017).

How should an IVF laboratory prove that its environment is under control?

A robust laboratory does not rely on a single temperature or gas reading. It monitors the complete system.

International IVF Laboratory Reference Framework

These values require an important distinction: not every number in IVF laboratory practice represents a universal international consensus limit. Gas concentrations and pH targets depend on the culture system, while osmolality, handling times, equipment recovery and consumable acceptance criteria require manufacturer specifications or laboratory validation.

The purpose of an international reference framework is therefore to define the parameters requiring control and the evidence hierarchy behind them, rather than impose identical numerical limits on every laboratory.

The strongest laboratory systems combine environmental monitoring with equipment validation, calibration, preventive maintenance, alarms, documented corrective actions and trend analysis. ESHRE recommendations specifically emphasise validation and regular maintenance of critical equipment, calibrated measurement systems and documented corrective action when parameters fall outside established acceptance ranges (ESHRE Good Practice in IVF Lab Working Group, 2026).

This evidence hierarchy also prevents a common mistake in IVF laboratory management: treating every variable as equally important. Some factors have direct physiological relevance; others primarily function as risk-control measures; and some laboratory practices remain supported mainly by expert consensus rather than high-level clinical trials.

The objective is not to create a laboratory in which every parameter remains mathematically identical at every moment. The objective is to establish a controlled, measurable and reproducible IVF laboratory environment in which clinically important deviations are detected, investigated and corrected.

In contemporary embryology, the critical question is no longer simply whether an incubator reaches its programmed set point.

It is whether the IVF laboratory environment experienced by the embryo is controlled, measurable and reproducible throughout the entire laboratory workflow.”

Written by Saadat Hassan
Senior Clinical Embryologist / IVF and Embryology
BSc (Hons) Medical Laboratory Technology
King Edward Medical University, Lahore, Pakistan

References

Title: ESHRE recommendations on Good Practice in the IVF laboratory

Authors: ESHRE Good Practice in the IVF Lab Working Group, Gemma Arroyo, Amy Barrie, Giovanni Coticchio, Thomas Ebner, Jackson Kirkman-Brown, Nathalie Le Clef, Kersti Lundin, Cristina Magli, Marina Quesada Martinez, Maria José de los Santos Molina, Kelly Tilleman, Ioannis Sfontouris

You can read the Full Article in Human Reproduction.

Title: Oxygen Equilibration Dynamics in Assisted Reproductive Technology Embryo Culture Media

Authors: Sanjana Kulkarni, Bailey K Morris, Sacha A Krieg, Thomas O’Leary, Adam Krieg

You can read the Full Article in the Journal of Assisted Reproduction and Genetics.

Title: Culture media for human pre‐implantation embryos in assisted reproductive technology cycles

Authors: Maitane Laverde, Miriam Zagers, Madelon van Wely, MA Youssef, Sebastiaan Mastenbroek

You can read the Full Article in the Cochrane Database of Systematic Reviews.

Title: The Vienna consensus: report of an expert meeting on the development of ART laboratory performance indicators

Authors: ESHRE Special Interest Group of Embryology and Alpha Scientists in Reproductive Medicine

You can read the Full Article in Reproductive BioMedicine Online.

Other articles featuring Saadat Hassan on Fertility News.