How are the best embryos created and selected for IVF treatment?

During this event, Vladimiro Silva, Founder & IVF Lab Director at Ferticentro, Coimbra, Portugal, discussed embryo selection process in IVF treatment, offering invaluable insights and expertise.

The role of female age in egg quality

When we consider the eggs, female age is the most crucial factor. As presented in the graph from the Centers for Disease Control and Prevention (CDC) – a national public health agency of the United States, the probability of a pregnancy declines with female age.  The younger the woman, the better the quality of her eggs. The opposite is also true when comparing cycles using donor eggs, where the eggs are of good quality.

The impact of sperm quality

There were some studies in Denmark claiming evidence of decreasing sperm quality over the past 50 years. However, a study published in the British Medical Journal showed no significant downward trend in sperm quality. Many factors can affect sperm quality, including exposure, lifestyle, toxicants, and alcohol.

For instance, a study from Denmark compared sperm quality in different seasons and locations, showing that sperm quality tends to be better in the winter. This illustrates the need to be cautious when interpreting these statistics. Factors such as exposure, and lifestyle can affect sperm quality.

Sperm takes around 90 days to be produced, and there are fluctuations within the same men throughout the year. It’s crucial to consider various factors that affect sperm quality. Good sperm and good eggs are essential for creating good embryos.

A study in human reproduction found that the egg contribution to embryo quality is about 70 to 80%, while the sperm contribution ranges from 10 to 15%. When the paternal component is abnormal, it can significantly impact embryo development and pregnancy.

Creating the best embryos

There are two main techniques for creating the best embryos. The first is classic IVF, where we stimulate the woman’s ovaries, collect the eggs, fertilize them with sperm, and transfer the resulting embryos to the womb. The second technique, ICSI (Intracytoplasmic Sperm Injection), involves injecting a single sperm directly into the egg. ICSI is the most commonly used IVF technique, and it has greatly improved the success rates of IVF treatments.

Creating the best embryos requires state-of-the-art laboratories, highly trained embryologists, and a commitment to ongoing improvement and quality control in IVF clinics. We need to ensure that we have the best conditions, culture media, and technology to achieve the best results. This systematic and analytical approach allows us to continually refine and enhance our IVF procedures.

Embryo classification in IVF labs

In IVF labs, daily work involves classifying embryos. Several methods exist, one of which is morphological classification, which has been in use for over 20 years. It relies on static images and was used before the advent of incubators with built-in video cameras. Embryos were taken from the incubator, observed under a microscope, and classified based on visible characteristics. For example, embryo ‘A’ with two pronuclei (from both parents) and two polar bodies is considered a good and normal fertilization. Embryo ‘B,’ with three pronuclei, suggesting an abnormal number of chromosomes, may be excluded.

Morphological classification, while historically useful, has limited correlation with genetic viability, especially when evaluated using preimplantation genetic testing (PGT). Therefore, clinics now employ more advanced methods, such as PGT-A, both invasive and noninvasive, as well as artificial intelligence and morphokinetics.

Blastocyst formation and advanced classification

For a deeper understanding, consider the development of blastocysts. On day four, embryos progress to the morula stage, with around 16 compacted cells. On day five, blastocysts begin to form, exhibiting an inner cell mass and a trophectoderm. Well-defined blastocysts with clear areas are considered to have excellent prognosis. On day six, embryos grow so large that they become challenging to observe under a microscope.

Previously, embryos were regularly removed from incubators for observation, exposing them to potential temperature fluctuations, light, and pH changes. To minimize such disruptions, many IVF clinics now employ time-lapse technology, with built-in video cameras within incubators.

While morphological classification remains a part of IVF practices, it’s no longer the sole determinant of embryo selection. Advanced techniques, such as PGT-A, noninvasive methods, and AI, have transformed how embryos are evaluated and chosen for transfer or freezing. IVF labs have shifted from relying solely on morphological classification to incorporate more sophisticated methods that enhance the likelihood of successful implantation and a healthy pregnancy. The field continues to evolve with advances in technology and understanding.

Embryoscope is an incubator equipped with an integrated video camera. This device enables embryologists to cultivate embryos continuously, beginning immediately after sperm insertion into the egg. Using the embryoscope, the embryologists gained valuable insights into the development of embryos. With real-time observation, they can monitor the intricate processes occurring inside the incubator. For example, embryologists observe the development of embryos.

Analyzing embryo development with AI

As we explore the use of artificial intelligence in assisted reproduction, it’s important to discuss the application of AI in embryo assessment and selection. AI holds immense potential in the field of assisted reproduction. While we currently rely more on embryologists than machines, AI’s progress promises to enhance our understanding and selection of embryos. AI can see aspects that the human eye might overlook and analyze embryo development in a systematic and reproducible manner.

Within AI, machine learning and deep learning are crucial. Machine learning assesses fixed embryo images, while deep learning observes the embryo’s evolution through raw images, making it a powerful tool.

Several AI methods, such as EMA and the iDAScore, effectively identify high-quality embryos, simplifying the assessment process and improving consistency and accuracy. Comparing different scoring methods, EMA has shown slight superiority over manual evaluation.

AI in reproductive science is rapidly evolving, offering great promise for embryo selection and improving IVF success rates. While we have not reached complete reliance on machines, AI is becoming an invaluable tool in the field of assisted reproduction, providing us with new ways to select the best embryos.