Culturing human embryos under optimal conditions is essential for the success of an in vitro fertilization (IVF) program. Equally important is the ability to accurately assess and rank embryos based on quality, enabling the transfer of the embryo with the highest developmental potential first. This approach can shorten the time to achieve pregnancy, although it does not necessarily improve cumulative pregnancy or live birth rates. It also supports and promotes the practice of single embryo transfer, thereby enhancing safety for both the mother and the child.

Time-lapse imaging technology introduces the concept of stable culture environments combined with continuous monitoring and documentation of embryo development. Despite these advancements, embryo quality assessment—even when based on large datasets or time-lapse systems—still relies largely on subjective and intermittent annotations of morphological features and developmental timings.

Moreover, the development of robust and universally applicable algorithms is hindered by significant variations in culture conditions across IVF laboratories. Emerging methodologies using machine learning offer a promising alternative: by analyzing every frame of time-lapse recordings, these systems can identify patterns associated with clinical outcomes. In the future, such approaches may lead to more accurate and unbiased embryo selection.

The success of an in vitro fertilization (IVF) program largely depends on the quality of the laboratory environment and the expertise of the embryologists. A well-functioning, quality-controlled laboratory is essential to ensure optimal outcomes. Today’s IVF laboratories are highly specialized and technically advanced facilities. Key components include laminar airflow (LAF) workstations, incubators, and high-resolution microscopes all of which are designed to provide clean, controlled environments for the safe handling, culture, and evaluation of gametes and embryos.

The primary tasks within the IVF laboratory are to optimize, to the best of current scientific understanding, both the environment and the handling of gametes and embryos. Another key responsibility is to evaluate, rank, and select embryos in order to maximize the likelihood of achieving a live birth. One of the main challenges in in vitro embryo culture is maintaining conditions that closely resemble the natural in vivo environment.

Throughout the assisted reproduction technology (ART) process, embryos are typically transferred between culture dishes and evaluated at specific time points. Each time an embryo is removed from the incubator, fluctuations in temperature and pH can occur in the culture medium, thereby altering the embryo’s microenvironment. Such changes are believed to impose metabolic stress on the embryo, potentially impacting its development and overall quality.

To mitigate this risk, it is essential to minimize the duration embryos and oocytes spend outside the controlled incubator conditions. As the practice of blastocyst culture where embryos are maintained in vitro for extended periods becomes increasingly common, maintaining a stable and uninterrupted culture environment is more critical than ever.

n the early days of IVF, embryos were cultured in a simple medium composed mainly of buffered salt solution and patient serum, which supported development for only 2–3 days. To extend in vitro culture, improved formulations known as sequential media were developed. These provide stage-specific nutrients, mimicking the embryo’s journey from the fallopian tube to the uterus.

More recently, with the advent of closed culture systems such as time-lapse incubators, interest has shifted back toward single-step media. These media are designed to contain all the necessary components to support development up to the blastocyst stage, allowing the embryo to selectively utilize nutrients as needed. This approach enables continuous, undisturbed culture, aligning with the principles of stable culture environments.

Several studies have shown that culturing embryos in specialized dishes within closed time-lapse systems equipped with continuous image capture does not negatively impact embryo development when compared to sibling oocytes cultured in conventional systems. Fertilization rates, embryo quality at the cleavage and blastocyst stages, and ongoing pregnancy rates appear comparable between both approaches.

Beyond developmental outcomes, time-lapse technology offers notable logistical advantages in the IVF laboratory. It allows continuous, non-invasive monitoring of embryo morphology and developmental timing without disturbing the culture environment. This supports deeper insights into embryo behavior (e.g., irregular cleavages), and enables detailed studies correlating developmental kinetics with metabolic and environmental parameters such as oxygen levels, temperature, and pH.

The captured videos facilitate comparison across different culture conditions and patient profiles, while also serving as valuable tools for embryologist training and the validation of embryo scoring systems.

When single-step culture media are used, embryos can remain undisturbed within the time-lapse incubator from the moment of fertilization (or ICSI/denudation) until transfer or cryopreservation. This streamlines laboratory workflows and allows embryo assessment at any convenient time during the workday.

The future of time-lapse imaging in IVF is closely tied to advances in artificial intelligence and machine learning. These technologies are expected to enhance embryo selection by enabling objective, data-driven analysis of morphokinetic patterns associated with implantation potential. Integrating time-lapse data with non-invasive biomarkers—such as metabolomic profiles or environmental monitoring—may lead to more comprehensive and personalized embryo assessments. Furthermore, as large annotated image databases grow, time-lapse systems will increasingly support automated embryo scoring, training for embryologists, and standardization of evaluation criteria across clinics. Ultimately, these innovations aim to improve live birth rates, reduce subjectivity, and support safer, more efficient single embryo transfer strategies.

While current evidence does not conclusively demonstrate that time-lapse technology whether as a closed culture system alone or in combination with morphokinetic algorithms improves embryo quality, selection accuracy, or IVF success rates, it remains a valuable tool in the embryology laboratory. Its primary benefits lie in providing a controlled, stable culture environment and generating extensive developmental data. Although existing algorithms have yet to show a clear advantage in clinical outcomes, ongoing efforts in data standardization and advanced analysis may ultimately lead to the development of more reliable and effective embryo selection tools in the future.