{"id":39692,"date":"2025-06-23T12:55:47","date_gmt":"2025-06-23T10:55:47","guid":{"rendered":"https:\/\/urecentrogutenberg.es\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/"},"modified":"2025-06-23T12:55:47","modified_gmt":"2025-06-23T10:55:47","slug":"embryo-classification-by-quality-for-in-vitro-fertilisation-treatment","status":"publish","type":"post","link":"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/","title":{"rendered":"Embryo classification by quality for in vitro fertilisation treatment"},"content":{"rendered":"<p>The biggest challenge for an in\u00a0<a href=\"https:\/\/urecentrogutenberg.es\/en\/in-vitro-fertilisation\/\" target=\"_blank\" rel=\"noopener noreferrer\">vitro fertilisation\u00a0<\/a>(IVF) laboratory is selecting the embryo which has the greatest potential to result in a pregnancy. That\u2019s why today we want to explain\u00a0<strong>how embryo classification works\u00a0<\/strong>in assisted reproduction, beginning by understanding that all Spanish clinics follow the criteria for evaluation and assessment as indicated by the Association for the Study of the Biology of Reproduction (ASEBIR).<\/p>\n<p>With this in mind, embryos can remain in the IVF laboratory\u00a0<strong>until day +6 of embryo development<\/strong>, where \u201cday zero\u201d is the day that the eggs are retrieved and inseminated with the spermatozoids (in other words, the day of\u00a0<a href=\"https:\/\/urecentrogutenberg.es\/en\/the-egg-retrieval-process-step-by-step\/\" target=\"_blank\" rel=\"noopener noreferrer\">ovule collection<\/a>).<\/p>\n<p>Keeping in mind the above, embryo transfer to the woman\u2019s uterus is\u00a0<strong>currently performed on either day +5 or day +6<\/strong>\u00a0of embryo development, depending on their growth and progress.<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Tabla de contenidos<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #3f3f3f;color:#3f3f3f\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #3f3f3f;color:#3f3f3f\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Embryo_classification_according_to_days_of_embryo_development\" >Embryo classification according to days of embryo development<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Day_0\" >Day 0<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Embryos_on_day_1\" >Embryos on day 1<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Embryos_on_day_2-3\" >Embryos on day 2-3<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Embryos_on_day_4\" >Embryos on day 4<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Embryos_on_day_5-6\" >Embryos on day 5-6<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Criteria_that_are_followed_for_embryo_classification_in_IVF\" >Criteria that are followed for embryo classification in IVF<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#How_embryos_are_classified_in_IVF\" >How embryos are classified in IVF<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Additional_information_about_embryo_classification_for_IVF\" >Additional information about embryo classification for IVF<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#What_is_the_importance_of_embryo_classification_in_IVF_treatment\" >What is the importance of embryo classification in IVF treatment?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-classification-by-quality-for-in-vitro-fertilisation-treatment\/#Have_technological_advances_in_recent_years_changed_the_way_embryos_are_evaluated\" >Have technological advances in recent years changed the way embryos are evaluated?<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"Embryo_classification_according_to_days_of_embryo_development\"><\/span>Embryo classification according to days of embryo development<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>In order to understand how we classify embryos based on their quality, we must first clearly understand\u00a0<strong>how they develop day by day\u00a0<\/strong>from the very first moment they are with us in the laboratory. We will explain this next.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Day_0\"><\/span>Day 0<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>As we mentioned before, day 0 is the day when\u00a0<strong>the eggs are obtained during the ovule retrieval procedure and are inseminated\u00a0<\/strong>with the spermatozoids through intracytoplasmic sperm microinjection (also known as ICSI).<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Embryos_on_day_1\"><\/span>Embryos on day 1<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>On day 1\u00a0<strong>we evaluate fertilisation<\/strong>. An ovule which has fertilised correctly (called a zygote), will have two pronuclei (one from the spermatozoid and the other from the egg),\u00a0and two polar bodies.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Embryos_on_day_2-3\"><\/span>Embryos on day 2-3<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Between 25 and 27 hours following fertilisation\u00a0<strong>the first round of cell division, or mitosis,\u00a0<\/strong>can be observed, and afterward the embryo will continue dividing. The\u00a0<strong>ideal number of cells we would like to see in an embryo is 4 cells on day 2 of development, and 8 cells on day 3.<\/strong><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Embryos_on_day_4\"><\/span>Embryos on day 4<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>At this stage the cells of the embryo begin to\u00a0<strong>compact<\/strong><strong>\u00a0and to form small unions<\/strong>\u00a0among each other, resulting in what is known as a morula.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Embryos_on_day_5-6\"><\/span>Embryos on day 5-6<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>This is the final day that the embryos are with us. At this stage the embryo becomes a\u00a0<a href=\"https:\/\/urecentrogutenberg.es\/en\/what-is-culture-to-blastocyst-and-why-do-we-use-it-in-assisted-reproduction\/\" target=\"_blank\" rel=\"noopener noreferrer\">blastocyst<\/a>\u00a0<strong>that is ready to be transferred\u00a0<\/strong>and\/or frozen through the\u00a0<a href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-freezing-frequently-asked-questions\/\" target=\"_blank\" rel=\"noopener noreferrer\">process of vitrification<\/a>. This blastocyst is uniquely structured as it has a central cavity (blastocele),\u00a0and two different cell groups: the\u00a0trophectoderm\u00a0(which will become the placenta and non-embryo tissue), and the inner cell mass or ICM (which will make up the tissue of the embryo).<\/p>\n<p>In order to better understand the\u00a0<strong>process of development which is essential<\/strong>\u00a0to classifying embryos, you can watch the following video in which the cell division we\u2019ve just explained can be perfectly observed. What you\u2019ll see in the video is a beautiful pregnancy captured using the\u00a0<strong>EmbryoScope, a powerful time-lapse incubator which our assisted reproduction clinic was the first to use in Malaga<\/strong>.<\/p>\n<p><iframe loading=\"lazy\" title=\"BONITO EMBARAZO CON EMBRYOSCOPE\" src=\"https:\/\/www.youtube.com\/embed\/DE3Ku0MDCUk?feature=oembed\" width=\"500\" height=\"375\" allowfullscreen=\"allowfullscreen\" data-mce-fragment=\"1\"><\/iframe><\/p>\n<h2><span class=\"ez-toc-section\" id=\"Criteria_that_are_followed_for_embryo_classification_in_IVF\"><\/span>Criteria that are followed for embryo classification in IVF<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Now that we understand how embryos develop day by day, we\u2019re going to explain\u00a0<strong>what parameters are taken into consideration\u00a0<\/strong>when embryos are classified.Essentially, the following factors are evaluated:<\/p>\n<ul>\n<li><strong>The number of cells and their symmetry<\/strong>, in other words, the similarity or difference in size among the different cells in the embryo as it continues to divide.<\/li>\n<li><strong>The rate of embryo division<\/strong>, and its development from the first day until day +5 or +6, the point at which a viable, properly developing embryo should reach blastocyst stage.<\/li>\n<li><strong>The percentage and type of cell fragmentation<\/strong>. Fragmentation refers to tiny, leftover pieces of cells that surround the embryo. In a viable embryo, the amount of fragmentation may vary between 0 to 35 or 40 %. The problem with cell fragmentation is that these fragments may make it more difficult for the embryo to divide and develop at the proper rate. This means that the more fragmentation an embryo has, the less likely it is to result in a pregnancy.<\/li>\n<li><strong>Morphology of the blastocyst<\/strong>. Blastocyst stage is the stage before embryo implantation can take place and lead to a pregnancy. The better an embryo has developed and the more favourable its appearance once it reaches blastocyst stage, the more likely it is to implant.<\/li>\n<li><strong>Other parameters<\/strong>\u00a0such as the presence of vacuoles, cells with more than one nucleus, and other factors such as the appearance and thickness of the external membrane which covers and protects the embryo.<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"How_embryos_are_classified_in_IVF\"><\/span>How embryos are classified in IVF<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Keeping in mind the criteria we have just discussed, the individual on the medical team at an assisted reproduction clinic who is responsible for monitoring and evaluating embryo development on a daily basis from the time they first fertilise\u00a0<strong>is\u00a0the embryologist<\/strong>.<\/p>\n<p>The task of daily monitoring will allow the embryologist to classify the embryos and give them\u00a0<strong>different grades depending on their quality<\/strong>:<\/p>\n<ul>\n<li><strong>A quality<\/strong>: optimal quality embryos with maximum implantation potential.<\/li>\n<li><strong>B quality<\/strong>: good quality embryos with good implantation potential.<\/li>\n<li><strong>C quality<\/strong>: intermediate quality embryos with intermediate implantation potential.<\/li>\n<li><strong>D quality<\/strong>: poor quality embryos with poor implantation potential.<\/li>\n<\/ul>\n<p>Depending on the quality assigned to an embryo and the likelihood that it will implant,\u00a0<strong>the doctor, together with the patients, will decide\u00a0<\/strong>which embryos will be transferred and which will be cryopreserved in the event that there is more than one viable embryo with potential to result in a pregnancy. Statistically speaking, A-quality embryos are more likely to lead to a positive pregnancy test.<\/p>\n<p>All embryos that are viable for embryo transfer have the ability to result in a pregnancy that goes to term and leads to a healthy baby at home. Transferring intermediate or poor quality embryos (C or D quality),\u00a0<strong>does not have any impact and does not play any role in the health of the baby<\/strong>. Children born as a result of in vitro fertilisation treatment have the same chances of having an illness as children who were conceived naturally. It is very important to remember that having a child with an illness is not related to the quality of the embryos that are used in IVF treatment.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Additional_information_about_embryo_classification_for_IVF\"><\/span>Additional information about embryo classification for IVF<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>One of the individuals with the most knowledge about embryo classification at URE Centro Gutenberg is\u00a0<strong>Dr. Bel\u00e9n Buch, laboratory manager and embryologist\u00a0<\/strong>at our Unit and a board member for ASEBIR.<\/p>\n<p>We asked Dr. Buch a few\u00a0<strong>questions about embryo classification\u00a0<\/strong>so that you would have more information on this matter, as we appreciate that it is a topic that concerns many moms and couples who are undergoing fertility treatment.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"What_is_the_importance_of_embryo_classification_in_IVF_treatment\"><\/span>What is the importance of embryo classification in IVF treatment?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Proper classification of the embryos obtained through in vitro fertilisation is\u00a0<strong>essential to the final result of the treatment cycle<\/strong>. The importance of correctly evaluating and classifying embryos means that the team will be able to properly select which embryos to\u00a0<a href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-transfer-common-questions-about-this-assisted-reproduction-treatment\/\" target=\"_blank\" rel=\"noopener noreferrer\">transfer to the uterus<\/a>\u00a0and\/or which embryos to\u00a0<a href=\"https:\/\/urecentrogutenberg.es\/en\/embryo-freezing-frequently-asked-questions\/\" target=\"_blank\" rel=\"noopener noreferrer\">freeze<\/a>\u00a0in order to achieve a full-term pregnancy as quickly as possible.<\/p>\n<p>This is why training and experience is fundamental for embryologists in the IVF laboratory seeing as embryo culture, selection and classification are the\u00a0<strong>determining factors\u00a0for a successful outcome<\/strong>, i.e. a pregnancy, in cycles of in vitro fertilisation.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Have_technological_advances_in_recent_years_changed_the_way_embryos_are_evaluated\"><\/span>Have technological advances in recent years changed the way embryos are evaluated?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Absolutely, yes. Many technological advances have been focused on reducing stress on embryos while they\u2019re developing in the laboratory, and\u00a0<strong>embryo culture equipment are becoming increasingly better adapted\u00a0<\/strong>to what embryos need.<\/p>\n<p>But the real revolution in recent years has been\u00a0<strong>the emergence of incubators<\/strong>\u00a0that monitor embryo development using cameras that are incorporated right into the incubator itself. These incubators, such as the EmbryoScope, used by URE Centro Gutenberg for the first time in all of Malaga, provide us with an enormous amount of information and are revolutionising the processes of embryo classification and selection, thus increasing success rates for certain patients. It doesn\u2019t perform \u201cmiracles\u201d, but it helps us and provides reassurance\u00a0when it comes to justifying why we have chosen one embryo for transfer over another.<\/p>\n<p>We hope this article has cleared up any doubts you had about the process of embryo classification based on quality for in vitro fertilisation treatment. If you want more information, you can take a look at different articles in our\u00a0<a href=\"https:\/\/urecentrogutenberg.es\/en\/blog\/\" target=\"_blank\" rel=\"noopener noreferrer\">blog.<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The biggest challenge for an in\u00a0vitro fertilisation\u00a0(IVF) laboratory is selecting the embryo which has the greatest potential to result in a pregnancy. That\u2019s why today we want to explain\u00a0how embryo classification works\u00a0in assisted reproduction, beginning by understanding that all Spanish clinics follow the criteria for evaluation and assessment as indicated by the Association for the [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":34447,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[499,653,500],"tags":[512,543,550,712,713,711,544,714,715,716,565,518,508,503,514,510,710,505],"class_list":["post-39692","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-assisted-reproduction-treatments-and-techniques","category-interviews","category-laboratory-stuff","tag-assisted-reproduction-clinic-in-malaga","tag-centro-gutenberg-en","tag-centro-gutenberg-malaga-en","tag-classification-of-embryos","tag-embryo-classification","tag-embryo-quality","tag-embryo-selection","tag-embryo-type-a","tag-embryo-type-b","tag-embryo-type-c","tag-embryoscope-en","tag-fertility-clinic","tag-fertility-clinic-in-malaga","tag-in-vitro-fertilisation","tag-ivf","tag-ivf-clinic-in-malaga","tag-success","tag-ure-centro-gutenberg-en"],"_links":{"self":[{"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/posts\/39692","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/comments?post=39692"}],"version-history":[{"count":1,"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/posts\/39692\/revisions"}],"predecessor-version":[{"id":39695,"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/posts\/39692\/revisions\/39695"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/media\/34447"}],"wp:attachment":[{"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/media?parent=39692"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/categories?post=39692"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/urecentrogutenberg.es\/en\/wp-json\/wp\/v2\/tags?post=39692"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}