{"id":174,"date":"2026-09-15T08:06:42","date_gmt":"2026-09-15T08:06:42","guid":{"rendered":"https:\/\/ivfprep.guide\/articles\/?p=174"},"modified":"2026-10-16T08:05:00","modified_gmt":"2026-10-16T08:05:00","slug":"good-quality-5-day-embryo-blastocyst","status":"publish","type":"post","link":"https:\/\/ivfprep.guide\/articles\/good-quality-5-day-embryo-blastocyst\/","title":{"rendered":"Good Quality 5 Day Embryo Blastocyst: What the Grade Means"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><strong>A good quality 5 day embryo blastocyst is usually a full or expanded blastocyst whose inner cell mass and outer layer are both graded A or B, though clinics draw the line in slightly different places. 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A synthetic voice reads the article and announces each section title as it begins; tables are read row by row and the questions at the end are left out.<\/p>\n<audio class=\"msq-audio-player\" controls preload=\"metadata\" src=\"https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/10\/good-quality-5-day-embryo-blastocyst-audio-202610102020.mp3\"><\/audio>\n<nav class=\"msq-toc\" aria-label=\"In this article\"><p class=\"msq-toc-title\">In this article<\/p>\n<ol>\n<li data-start=\"0.0\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"0.0\" aria-label=\"Play from: Good Quality 5 Day Embryo Blastocyst: What the Grade Means\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">0:00<\/span><a href=\"#top\">Good Quality 5 Day Embryo Blastocyst: What the Grade Means<\/a><\/li>\n<li data-start=\"31.78\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"31.78\" aria-label=\"Play from: What does a blastocyst grade like 4BB actually stand for?\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">0:32<\/span><a href=\"#what-does-a-blastocyst-grade-like-4bb-actually-stand-for\">What does a blastocyst grade like 4BB actually stand for?<\/a><\/li>\n<li data-start=\"264.96\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"264.96\" aria-label=\"Play from: What counts as a good quality 5 day blastocyst?\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">4:25<\/span><a href=\"#what-counts-as-a-good-quality-5-day-blastocyst\">What counts as a good quality 5 day blastocyst?<\/a><\/li>\n<li data-start=\"330.46\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"330.46\" aria-label=\"Play from: How much does the grade change the chance of a live birth?\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">5:30<\/span><a href=\"#how-much-does-the-grade-change-the-chance-of-a-live-birth\">How much does the grade change the chance of a live birth?<\/a><\/li>\n<li data-start=\"372.76\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"372.76\" aria-label=\"Play from: Does the grade still matter if the embryo was genetically tested?\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">6:13<\/span><a href=\"#does-the-grade-still-matter-if-the-embryo-was-genetically-te\">Does the grade still matter if the embryo was genetically tested?<\/a><\/li>\n<li data-start=\"471.94\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"471.94\" aria-label=\"Play from: Is a day 5 blastocyst better than a day 6 one?\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">7:52<\/span><a href=\"#is-a-day-5-blastocyst-better-than-a-day-6-one\">Is a day 5 blastocyst better than a day 6 one?<\/a><\/li>\n<li data-start=\"525.8\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"525.8\" aria-label=\"Play from: What do people who transferred graded embryos report?\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">8:46<\/span><a href=\"#what-do-people-who-transferred-graded-embryos-report\">What do people who transferred graded embryos report?<\/a><\/li>\n<li data-start=\"654.62\"><button type=\"button\" class=\"msq-toc-play\" data-start=\"654.62\" aria-label=\"Play from: What does an embryo&#x27;s grade mean during the two week wait?\">&#x25B6;&#xFE0E;<\/button><span class=\"msq-toc-time\">10:55<\/span><a href=\"#what-does-an-embryo-s-grade-mean-during-the-two-week-wait\">What does an embryo&#x27;s grade mean during the two week wait?<\/a><\/li>\n<\/ol><\/nav>\n<p class=\"msq-audio-note\">Recorded 10 October 2026 from the article as published that day. 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your embryologist, and forum reports on success rates.<\/p>\n\n\n\n<div class=\"msq\" id=\"ms-quiz\" data-slug=\"good-quality-5-day-embryo-blastocyst\" data-category=\"Understanding IVF\" data-list=\"1\">\n<style>.msq,.msq-hook,.msq-box,.msq-end,.msq-tool{--msq-accent:#1F4E79;--msq-accent-text:#FFFFFF;--msq-line:#CBD8E6;--msq-warn:#B4531A;--msq-muted:#4A5560;--msq-tint:#EEF3F8;--msq-base:#FFFFFF}\n.msq{margin:1.25em 0 1.75em}\n.msq-hook{border-left:3px solid var(--msq-accent);padding:6px 14px;color:var(--msq-muted);font-size:.97em}\n.msq-box{background:var(--msq-tint);border:1px solid var(--msq-line);border-radius:12px;padding:0}\n.msq-box>summary{cursor:pointer;list-style:none;padding:14px 18px;font-weight:700;color:var(--msq-accent)}\n.msq-box>summary::-webkit-details-marker{display:none}\n.msq-box>summary::before{content:\"+\";display:inline-block;width:1.1em;font-weight:800}\n.msq-box[open]>summary::before{content:\"\\00d7\"}\n.msq-body{padding:2px 18px 18px}\n.msq-intro{margin:0 0 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var(--msq-accent);border-radius:12px;text-align:center;background:var(--msq-tint)}\n.msq-end p{margin:0 0 12px}\n.msq-end .msq-body{text-align:left;padding:16px 0 0}\n.msq-end .msq-start-test[hidden]{display:none}\n.msq-tool{margin:1.5em 0;padding:18px 20px;background:var(--msq-tint);border:1px solid var(--msq-line);border-radius:12px}\n.msq-tool h3{margin:0 0 6px;font-size:1.15em}\n.msq-tool p{margin:0 0 10px}\n.msq-tool .msq-note{font-size:.85em;color:var(--msq-muted);margin:10px 0 0}\n.msq-check label{display:flex;gap:10px;align-items:flex-start;padding:9px 0;border-bottom:1px solid var(--msq-line);cursor:pointer;line-height:1.4}\n.msq-check label:last-of-type{border-bottom:0}\n.msq-check input{margin-top:5px;flex:0 0 auto;width:18px;height:18px;accent-color:var(--msq-accent)}\n.msq-check-count{font-weight:700;margin:10px 0 0}\n.msq-verdict-box{margin:12px 0 0;padding:10px 14px;border-radius:8px;background:var(--msq-base);border-left:3px solid var(--msq-warn)}\n.msq-verdict-box[hidden]{display:none}\n.msq-calc{display:grid;grid-template-columns:1fr 1fr;gap:10px 16px}\n.msq-calc label{display:flex;flex-direction:column;gap:4px;font-size:.92em}\n.msq-calc input,.msq-calc select{padding:8px 10px;border:1px solid var(--msq-muted);border-radius:8px;font:inherit;background:#fff}\n.msq-calc-out{grid-column:1 \/ -1;margin-top:6px;padding:12px 14px;background:var(--msq-base);border-radius:8px;border:1px solid var(--msq-line)}\n.msq-calc-out strong{font-size:1.15em}\n.msq-choose label{display:block;padding:9px 12px;margin:0 0 8px;background:var(--msq-base);border:1px solid var(--msq-line);border-radius:8px;cursor:pointer}\n.msq-choose input{margin-right:8px;accent-color:var(--msq-accent)}\n.msq-choice-result{margin-top:10px;padding:12px 14px;background:var(--msq-base);border-left:3px solid var(--msq-accent);border-radius:0 8px 8px 0}\n.msq-choice-result[hidden]{display:none}\n@media (max-width:600px){.msq-calc{grid-template-columns:1fr}}\nh2.wp-block-heading[id]{scroll-margin-top:24px}<\/style>\n<noscript><style>.msq-explain{display:block !important}<\/style><\/noscript>\n<details class=\"msq-box\">\n<summary>Think you already know this? Five questions, one minute.<\/summary>\n<div class=\"msq-body\">\n<p class=\"msq-intro\">Every answer is on this page. Answer from what you know now; the page fills in the rest.<\/p>\n<ol class=\"msq-list\">\n<li class=\"msq-q\" data-q=\"1\" data-answer=\"b\" data-title=\"What does a blastocyst grade like 4BB actually stand for?\" data-section=\"#what-does-a-blastocyst-grade-like-4bb-actually-stand-for\">\n<p class=\"msq-question\">1. In the Gardner grading system, what does the first letter of the grade represent?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 1 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">The expansion stage of the fluid cavity<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">The inner cell mass that becomes the baby<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">The outer layer that becomes the placenta<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>The first letter represents the inner cell mass, which eventually becomes the baby, as described in the <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC7943864\/\" target=\"_blank\" rel=\"noopener\">2021 study of 10,482 frozen single blastocyst transfers at Tongji Hospital in China<\/a>. <a class=\"msq-section\" href=\"#what-does-a-blastocyst-grade-like-4bb-actually-stand-for\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"2\" data-answer=\"a\" data-title=\"What counts as a good quality 5 day blastocyst?\" data-section=\"#what-counts-as-a-good-quality-5-day-blastocyst\">\n<p class=\"msq-question\">2. Why might two fertility clinics describe the exact same embryo with different quality grades?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 2 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">There is no single legal definition and visual assessment remains subjective<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Clinics are required by law to use completely different grading scales<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">Embryos physically change their shape every few minutes<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>The <a href=\"https:\/\/academic.oup.com\/humrep\/article\/40\/6\/989\/8120385\" target=\"_blank\" rel=\"noopener\">2025 revision of the ESHRE and ALPHA Istanbul consensus<\/a> notes that morphology assessment remains largely subjective and varies between observers. <a class=\"msq-section\" href=\"#what-counts-as-a-good-quality-5-day-blastocyst\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"3\" data-answer=\"b\" data-title=\"How much does the grade change the chance of a live birth?\" data-section=\"#how-much-does-the-grade-change-the-chance-of-a-live-birth\">\n<p class=\"msq-question\">3. What do large-scale studies show about the relationship between embryo grades and live birth rates?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 3 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Embryos graded C never result in a live birth<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Higher grades have higher group success rates, but lower grades still produce babies<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">The grade of a single embryo predicts its exact transfer outcome with certainty<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>In the <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC7943864\/\" target=\"_blank\" rel=\"noopener\">2021 study of 10,482 frozen single blastocyst transfers at Tongji Hospital in China<\/a>, higher-graded embryos had higher success rates as a group, but over a quarter of C-graded inner cell mass embryos still led to live births. <a class=\"msq-section\" href=\"#how-much-does-the-grade-change-the-chance-of-a-live-birth\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"4\" data-answer=\"b\" data-title=\"Does the grade still matter if the embryo was genetically tested?\" data-section=\"#does-the-grade-still-matter-if-the-embryo-was-genetically-te\">\n<p class=\"msq-question\">4. For embryos that have tested chromosomally normal, which factors remain significantly linked to live birth rates?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 4 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Only the expansion stage and the inner cell mass grade<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Only the outer layer grade and the day the embryo formed<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">None of the grading factors matter once an embryo is tested<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>According to the <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC9044033\/\" target=\"_blank\" rel=\"noopener\">2022 study from Zhengzhou University<\/a>, once an embryo tested normal, only the outer layer grade and the day it formed were significantly linked to live birth. <a class=\"msq-section\" href=\"#does-the-grade-still-matter-if-the-embryo-was-genetically-te\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"5\" data-answer=\"a\" data-title=\"Is a day 5 blastocyst better than a day 6 one?\" data-section=\"#is-a-day-5-blastocyst-better-than-a-day-6-one\">\n<p class=\"msq-question\">5. How did day 5 genetically tested normal embryos compare to day 6 ones in the 2022 Zhengzhou study?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 5 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Day 5 embryos had a 57.75% live birth rate compared to 41.67% for day 6<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Day 6 embryos had a higher live birth rate than day 5 embryos<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">Both days had identical live birth rates of exactly 50%<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>The <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC9044033\/\" target=\"_blank\" rel=\"noopener\">2022 study from Zhengzhou University<\/a> reported a live birth rate of 57.75% for day 5 blastocysts compared to 41.67% for day 6 blastocysts among tested normal embryos. <a class=\"msq-section\" href=\"#is-a-day-5-blastocyst-better-than-a-day-6-one\">Read the section<\/a><\/p>\n<\/li>\n<\/ol>\n<div class=\"msq-result\" hidden><\/div>\n<\/div>\n<\/details>\n<script>(function(){\n  if (window.__msqInit) { return; }\n  window.__msqInit = true;\n  var root = document.getElementById('ms-quiz');\n  if (!root) { return; }\n  var meta = { slug: root.getAttribute('data-slug'), category: root.getAttribute('data-category'),\n               list: root.getAttribute('data-list') || '1' };\n  function qs(el, s){ return el.querySelector(s); }\n  function qsa(el, s){ return Array.prototype.slice.call(el.querySelectorAll(s)); }\n  function track(name, params){\n    try { if (typeof gtag === 'function') { var p = params || {}; p.article = meta.slug; gtag('event', name, p); } } catch (e) {}\n  }\n  function jumpList(missed){\n    if (!missed.length) { return ''; }\n    return '<ul class=\"msq-jump\">' + missed.map(function(q){\n      return '<li><a href=\"' + q.getAttribute('data-section') + '\">' + q.getAttribute('data-title') + '<\/a><\/li>';\n    }).join('') + '<\/ul>';\n  }\n  function emailForm(){\n    return '<div class=\"msq-sub\"><p><strong>Get the next one.<\/strong> We publish new articles on ' + meta.category\n      + ' most weeks and recheck this page on Sundays. 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Calculators carry their own small script. *\/\n  function initTools(){\n    qsa(document, '.msq-check').forEach(function(box){\n      var key = 'msq-check-' + meta.slug + '-' + (box.getAttribute('data-id') || 'x');\n      var boxes = qsa(box, 'input[type=checkbox]'), count = qs(box, '.msq-check-count');\n      var yes = qs(box, '.msq-verdict-yes'), no = qs(box, '.msq-verdict-no');\n      var saved = {};\n      try { saved = JSON.parse(localStorage.getItem(key) || '{}'); } catch (e) {}\n      boxes.forEach(function(cb, i){ if (saved[i]) { cb.checked = true; } });\n      function refresh(){\n        var n = boxes.filter(function(cb){ return cb.checked; }).length, state = {};\n        boxes.forEach(function(cb, i){ if (cb.checked) { state[i] = 1; } });\n        try { localStorage.setItem(key, JSON.stringify(state)); } catch (e) {}\n        if (count) { count.textContent = n + ' of ' + boxes.length + (box.getAttribute('data-verb') || ' done'); }\n        if (yes && no) { yes.hidden = n === 0; no.hidden = n !== 0; }\n      }\n      boxes.forEach(function(cb){ cb.addEventListener('change', function(){ refresh(); track('tool_check', { tool: box.getAttribute('data-id') }); }); });\n      refresh();\n    });\n    qsa(document, '.msq-choose').forEach(function(box){\n      var results = qsa(box, '.msq-choice-result');\n      qsa(box, 'input[type=radio]').forEach(function(r){\n        r.addEventListener('change', function(){\n          results.forEach(function(el){ el.hidden = el.getAttribute('data-for') !== r.value; });\n          track('tool_choose', { tool: box.getAttribute('data-id'), choice: r.value });\n        });\n      });\n    });\n  }\n  \/\/ read progress: how far down the article the reader has scrolled, fired once per quarter\n  (function(){\n    var art = root.closest('article') || root.parentNode, fired = {};\n    function check(){\n      var top = art.getBoundingClientRect().top + window.pageYOffset, h = art.offsetHeight || 1;\n      var seen = (window.pageYOffset + window.innerHeight - top) \/ h * 100;\n      [25, 50, 75, 100].forEach(function(m){ if (seen >= m && !fired[m]) { fired[m] = true; track('read_progress', { percent: m }); } });\n    }\n    window.addEventListener('scroll', check, { passive: true }); window.addEventListener('load', check);\n  })();\n  if (document.readyState === 'loading') { document.addEventListener('DOMContentLoaded', initTools); } else { initTools(); }\n})();<\/script>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"what-does-a-blastocyst-grade-like-4bb-actually-stand-for\">What does a blastocyst grade like 4BB actually stand for?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Most clinics report a blastocyst with the Gardner system: one number and two letters. The number is how far the embryo has expanded. The first letter is the inner cell mass, the cluster that becomes the baby. The second letter is the trophectoderm, the outer layer that becomes the placenta. So 4BB is an expanded blastocyst with a B inner cell mass and a B outer layer. A bingo call, until somebody decodes it.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Here is each part in one sentence, set beside the live birth rates from a <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC7943864\/\" target=\"_blank\" rel=\"noopener\">2021 study of 10,482 frozen single blastocyst transfers at Tongji Hospital in China<\/a>, run between 2009 and 2018. Embryos that had genetic testing, and cycles using donor eggs, were excluded, and the average age of those who had a live birth was about 31. The stage 1 and 2 wording comes from a <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC12041180\/\" target=\"_blank\" rel=\"noopener\">2025 cohort study<\/a> that uses the same scale.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Grade<\/th><th>What it means in plain words<\/th><th>Live birth rate in the 2021 cohort<\/th><\/tr><\/thead><tbody><tr><td>Stage 1<\/td><td>Early blastocyst: the fluid cavity fills less than half the embryo<\/td><td>Not in the cohort<\/td><\/tr><tr><td>Stage 2<\/td><td>The cavity fills more than half the embryo<\/td><td>Not in the cohort<\/td><\/tr><tr><td>Stage 3<\/td><td>Full blastocyst: the cavity fills the whole embryo<\/td><td>37.07% (883 of 2,382)<\/td><\/tr><tr><td>Stage 4<\/td><td>Expanded: the cavity has grown and the outer shell is thinning<\/td><td>44.21% (3,230 of 7,306)<\/td><\/tr><tr><td>Stage 5<\/td><td>Hatching: the embryo is starting to push out of its shell<\/td><td>41.67% (195 of 468)<\/td><\/tr><tr><td>Stage 6<\/td><td>Hatched: the embryo is fully out of its shell<\/td><td>37.12% (121 of 326)<\/td><\/tr><tr><td>Inner cell mass A<\/td><td>Many cells, tightly packed<\/td><td>54.62% (538 of 985)<\/td><\/tr><tr><td>Inner cell mass B<\/td><td>Many cells, loosely grouped<\/td><td>41.29% (3,823 of 9,258)<\/td><\/tr><tr><td>Inner cell mass C<\/td><td>Very few cells<\/td><td>28.45% (68 of 239)<\/td><\/tr><tr><td>Outer layer A<\/td><td>Many cells forming a cohesive layer<\/td><td>52.74% (453 of 859)<\/td><\/tr><tr><td>Outer layer B<\/td><td>Few cells forming a loose layer<\/td><td>45.64% (2,939 of 6,439)<\/td><\/tr><tr><td>Outer layer C<\/td><td>Very few cells<\/td><td>32.57% (1,037 of 3,184)<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">Each row is one part of the grade, not a whole embryo. Rates from <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC7943864\/\" target=\"_blank\" rel=\"noopener\">Ai and colleagues, Frontiers in Endocrinology, 2021<\/a>, checked at source on 15 September 2026.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Two things in that table are worth a second look. The expansion rates do not climb in a straight line: stage 4 did better than stage 6. And B was by far the most common inner cell mass grade, 9,258 of 10,482 embryos. A B is not a warning. It is the middle of the pack.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1600\" height=\"900\" src=\"https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/10\/good-quality-5-day-embryo-blastocyst-chart.png\" alt=\"Bar chart of live birth rates by inner cell mass grades A, B, and C\" class=\"wp-image-543\" srcset=\"https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/10\/good-quality-5-day-embryo-blastocyst-chart.png 1600w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/10\/good-quality-5-day-embryo-blastocyst-chart-300x169.png 300w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/10\/good-quality-5-day-embryo-blastocyst-chart-1024x576.png 1024w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/10\/good-quality-5-day-embryo-blastocyst-chart-768x432.png 768w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/10\/good-quality-5-day-embryo-blastocyst-chart-1536x864.png 1536w\" sizes=\"auto, (max-width: 1600px) 100vw, 1600px\" \/><figcaption class=\"wp-block-image__caption\">Data from the 2021 study of 10,482 frozen single blastocyst transfers at Tongji Hospital.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"what-counts-as-a-good-quality-5-day-blastocyst\">What counts as a good quality 5 day blastocyst?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">There is no single legal definition, which is why two clinics can describe the same embryo differently. Across that whole 2021 cohort the live birth rate was 42 per cent, 4,429 of 10,482, and its authors found the inner cell mass the strongest single predictor.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1376\" height=\"768\" src=\"https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/journal-notes-about-good-quality-5-day-embryo-blastocyst.jpg\" alt=\"A pen over a blank notebook beside tea, ready for questions about a good quality 5 day embryo blastocyst.\" class=\"wp-image-172\" srcset=\"https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/journal-notes-about-good-quality-5-day-embryo-blastocyst.jpg 1376w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/journal-notes-about-good-quality-5-day-embryo-blastocyst-300x167.jpg 300w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/journal-notes-about-good-quality-5-day-embryo-blastocyst-1024x572.jpg 1024w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/journal-notes-about-good-quality-5-day-embryo-blastocyst-768x429.jpg 768w\" sizes=\"auto, (max-width: 1376px) 100vw, 1376px\" \/><figcaption class=\"wp-block-image__caption\">Writing down questions for the embryologist can be easier than remembering them on the phone.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">A <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC9044033\/\" target=\"_blank\" rel=\"noopener\">2022 study from Zhengzhou University<\/a> drew its lines differently. It called 4AA, 4AB and 4BA, and the same at stages 5 and 6, good; 4BB, 5BB and 6BB average; and anything with a C outer layer poor. By that scheme a 4BB is average, and by plenty of clinic leaflets it is good. Nobody is lying. They are using different rulers.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The ruler is also held by a person. The <a href=\"https:\/\/academic.oup.com\/humrep\/article\/40\/6\/989\/8120385\" target=\"_blank\" rel=\"noopener\">2025 revision of the ESHRE and ALPHA Istanbul consensus<\/a> on embryo assessment says morphology assessment &#8220;remains largely subjective&#8221; and varies between observers and laboratories. A grade is a careful visual judgement at one moment, not a measurement.<\/p>\n\n\n\n<div class=\"msq-tool msq-check\" data-id=\"embryo-grading-checklist\" data-verb=\" asked\">\n<h3>Questions to Ask Your Embryologist<\/h3>\n<p>Prepare for your next clinic call by checking off these key questions about your blastocyst&#8217;s development and grading scale.<\/p>\n<label><input type=\"checkbox\">What specific grading system does our laboratory use to evaluate blastocysts?<\/label>\n<label><input type=\"checkbox\">How does our clinic define a good, average, or poor quality embryo?<\/label>\n<label><input type=\"checkbox\">What was the expansion stage of our embryo on the day of grading?<\/label>\n<label><input type=\"checkbox\">What were the individual grades for the inner cell mass and the outer layer?<\/label>\n<label><input type=\"checkbox\">Was this embryo graded and frozen on day 5, day 6, or day 7?<\/label>\n<label><input type=\"checkbox\">How does our lab weigh the day of development against the letters when choosing embryos?<\/label>\n<p class=\"msq-check-count\"><\/p>\n<p class=\"msq-note\">Ticks are saved on this device only.<\/p>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"how-much-does-the-grade-change-the-chance-of-a-live-birth\">How much does the grade change the chance of a live birth?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Across thousands of transfers, a fair amount. In the 2021 cohort an A inner cell mass was followed by a live birth 54.62 per cent of the time and a C by 28.45 per cent. That gap is real, and pretending otherwise does nobody any favours.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">What those numbers cannot do is shrink down to one embryo. They are group rates from one hospital, among people averaging around 31, with that lab&#8217;s own culture and grading. More than a quarter of the C embryos became babies, and nearly half of the A embryos did not. A grade shifts the odds for a crowd. It does not tell anyone what their own embryo will do, and this site will not pretend to translate a grade into a personal chance.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"does-the-grade-still-matter-if-the-embryo-was-genetically-te\">Does the grade still matter if the embryo was genetically tested?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Less, but not zero. The <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC9044033\/\" target=\"_blank\" rel=\"noopener\">2022 Zhengzhou study<\/a> followed 393 single transfers of embryos that tested as chromosomally normal, from 431 testing cycles between June 2017 and March 2021, with an average age of about 32.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Group, tested normal embryos only<\/th><th>Live birth rate<\/th><\/tr><\/thead><tbody><tr><td>Good quality<\/td><td>55.56% (50 of 90)<\/td><\/tr><tr><td>Average quality (BB)<\/td><td>53.49% (69 of 129)<\/td><\/tr><tr><td>Poor quality (C outer layer)<\/td><td>45.40% (79 of 174)<\/td><\/tr><tr><td>Day 5 blastocysts<\/td><td>57.75% (123 of 213)<\/td><\/tr><tr><td>Day 6 blastocysts<\/td><td>41.67% (75 of 180)<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">Source: <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC9044033\/\" target=\"_blank\" rel=\"noopener\">Li and colleagues, Frontiers in Endocrinology, 2022<\/a>, checked at source on 15 September 2026. One centre, one population.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The authors found that, once an embryo tested normal, only the outer layer grade and the day it formed were significantly linked to live birth. Grade did show up earlier, in the testing: among women under 35, 62.90 per cent of good quality embryos were chromosomally normal against 32.46 per cent of poor ones. So grade and test result are related, loosely, and a C can still test normal while an AA does not. Our guide to <a href=\"https:\/\/ivfprep.guide\/articles\/euploid-embryo\/\">what a euploid embryo result actually means<\/a> covers what that chromosomally normal call does and does not promise for a single transfer. Some tested embryos come back neither normal nor abnormal but somewhere in between, and our guide to <a href=\"https:\/\/ivfprep.guide\/articles\/mosaic-embryo-ivf\/\">mosaic embryo results and what the trials show<\/a> covers that third label.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"is-a-day-5-blastocyst-better-than-a-day-6-one\">Is a day 5 blastocyst better than a day 6 one?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">In both studies here, day 5 blastocysts did better as a group. In the tested embryos above the gap was 57.75 against 41.67 per cent. The 2021 cohort also reported higher live birth rates for day 5, though its published figures do not give a clean rate for each day. Whether growing embryos to day 5 at all changes the result across a whole cycle is a separate question, covered in <a href=\"https:\/\/ivfprep.guide\/articles\/blastocyst-treatment\/\">our look at the Cochrane evidence on blastocyst treatment<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Labs look at embryos at set times, so a blastocyst recorded on day 6 may have been only hours behind. How a clinic weighs the day against the letters is a lab decision this site cannot second guess. Our <a href=\"https:\/\/ivfprep.guide\/articles\/frozen-embryo-transfer-timeline\/\">frozen embryo transfer timeline<\/a> covers what happens to the embryo after it is warmed, including the re-expansion the embryologist looks for, and the <a href=\"https:\/\/ivfprep.guide\/articles\/assisted-zona-hatching\/\">guide to assisted zona hatching<\/a> explains the shell that stages 5 and 6 are escaping. For what day 5, day 6 and day 7 actually represent before any grading happens, see our piece on <a href=\"https:\/\/ivfprep.guide\/articles\/blastocyst-stages\/\">blastocyst stages, day by day<\/a>. The studies that compared re expanded and collapsed blastocysts after warming are gathered in one table in our page on <a href=\"https:\/\/ivfprep.guide\/articles\/embryo-hatching-after-thaw\/\">what embryo hatching after thaw means<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"what-do-people-who-transferred-graded-embryos-report\">What do people who transferred graded embryos report?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">These are accounts, not evidence, and they come with a built in tilt. We read three threads in the r\/IVF community, roughly 180 comments, dated November 2025 to September 2026. Two of the three asked outright for success stories, and a thread that asks for successes collects successes. The quiet transfers that did not work mostly stay out of it, which is the forum problem this site keeps running into, pointed the other way.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In a <a href=\"https:\/\/www.reddit.com\/r\/IVF\/comments\/1ozjm1s\/if_you_had_a_healthy_baby_via_ivf_and_know_what\/\" target=\"_blank\" rel=\"noopener\">November 2025 thread<\/a>, someone with six frozen blastocysts from 3AA down to 4CC asked whether lower grades ever became babies. Replies listed live births from grades including 2AA, 3BC, 4BC and CC. The same thread held the other side: one person transferred three tested 4BB embryos, with one failing, one live birth and one miscarriage, and another said their four highest graded embryos all tested abnormal. One commenter regretted asking for the grade at all, because a 3BB sent them spiralling.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A <a href=\"https:\/\/www.reddit.com\/r\/IVF\/comments\/1rjl9ik\/what_were_your_embryo_grades_and_did_they_turn\/\" target=\"_blank\" rel=\"noopener\">February 2026 thread<\/a> compared grades with test results. Several people said their AA embryos tested abnormal while BC or CC embryos tested normal; one reported the reverse across three retrievals; one had two tested CC embryos that did not implant. A commenter with a statistics background made the fairest point of the lot: big studies describe groups, and one person&#8217;s handful of embryos can land anywhere.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In a <a href=\"https:\/\/www.reddit.com\/r\/IVF\/comments\/1w4d932\/has_anyone_had_success_with_a_b_grade_embryo\/\" target=\"_blank\" rel=\"noopener\">September 2026 thread<\/a> about B grades, most of the 50 or so replies were pregnancies and children from 2BB to 6CB, plus one 3AA that did not work. The familiar line that grading is just a beauty contest appeared, and was challenged by others pointing to studies. One person who had just transferred a 2B embryo said they felt defeated before reading the replies.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Where the accounts agree with the studies: lower grades do produce live births, and grade and test results do not line up one to one. Where they part company: the beauty contest line. Both large studies above found real group differences by grade. The forum is right that a grade cannot tell you your outcome, and wrong that it means nothing at all.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"what-does-an-embryo-s-grade-mean-during-the-two-week-wait\">What does an embryo&#8217;s grade mean during the two week wait?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Nothing you can feel. No symptom, and no absence of symptoms, tells you anything about the grade of the embryo that was transferred or how it is doing. Our piece on <a href=\"https:\/\/ivfprep.guide\/articles\/successful-implantation-without-bleeding\/\">why no bleeding and no symptoms is not evidence either way<\/a> covers why the body stays quiet whatever is happening, and the <a href=\"https:\/\/ivfprep.guide\/articles\/beta-hcg-test-explained\/\">beta hCG test explained<\/a> sets out what the blood test on the clinic&#8217;s date can and cannot say.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1376\" height=\"768\" src=\"https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/woman-in-garden-reflecting-on-good-quality-5-day-embryo-blastocyst.jpg\" alt=\"A woman holding a mug in a garden, thinking about her good quality 5 day embryo blastocyst.\" class=\"wp-image-173\" srcset=\"https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/woman-in-garden-reflecting-on-good-quality-5-day-embryo-blastocyst.jpg 1376w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/woman-in-garden-reflecting-on-good-quality-5-day-embryo-blastocyst-300x167.jpg 300w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/woman-in-garden-reflecting-on-good-quality-5-day-embryo-blastocyst-1024x572.jpg 1024w, https:\/\/ivfprep.guide\/articles\/wp-content\/uploads\/2026\/09\/woman-in-garden-reflecting-on-good-quality-5-day-embryo-blastocyst-768x429.jpg 768w\" sizes=\"auto, (max-width: 1376px) 100vw, 1376px\" \/><figcaption class=\"wp-block-image__caption\">No grade can be felt in the two week wait, however long the afternoon.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Your clinic knows your embryos, your lab&#8217;s grading habits and your protocol, and this page knows none of them. If you have heavy bleeding, severe pain, or anything that worries you, contact your clinic. Questions about why a particular embryo was chosen belong with your embryologist or doctor, who can explain their own scale.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>This article is general information, not personal medical advice. Please speak to your fertility clinic or another qualified professional about your own situation.<\/em><\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"frequently-asked-questions\">Frequently asked questions<\/h2>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list \">\n<div id=\"faq-q-1\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Can a blastocyst&#8217;s grade change after it is thawed?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>The expansion number can. Blastocysts shrink when they are frozen and re-expand after warming, so an embryo may look more or less expanded on transfer day than on the day it was graded. Your clinic can tell you what the embryologist saw after warming.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-2\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Do all clinics use the Gardner grading system?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>No. It is the most widely used, but some clinics use simpler good, fair and poor categories and some use other scales entirely. A grade only makes sense next to the scale it came from, so it is reasonable to ask which one your clinic uses.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-3\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Why did my clinic not tell me the embryo grade?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Some clinics do not share grades routinely, and people on forums report being told it was to avoid unnecessary worry. Practice varies. If you want to know, you can ask, and your clinic can explain what the grade does and does not mean for your treatment.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-4\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Is a 4BB blastocyst poor quality?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Not in the studies checked here. One 2022 study classed BB as average rather than poor, many clinics call it good, and B was the most common inner cell mass grade in a cohort of more than 10,000 transfers.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-5\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Can grading show whether an embryo is chromosomally normal?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>No. In one 2022 study, poorer grades were less often chromosomally normal as a group, but many good quality embryos tested abnormal and many poor ones tested normal. Only genetic testing, where it is offered and chosen, looks at chromosomes.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-6\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Does a higher grade embryo cause more symptoms in the two week wait?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>There is no evidence that embryo grade shows up as symptoms. Symptoms in the two week wait are not a reliable sign of anything about the embryo, and the blood test on your clinic&#8217;s date is the only way to know the result.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"msq-end\" id=\"ms-quiz-end\">\n<p><strong>Finished the page?<\/strong> The same five questions from the top, to see what stuck.<\/p>\n<button type=\"button\" class=\"msq-btn msq-start-test\">Test Your Understanding of This Article<\/button>\n<div class=\"msq-mount\"><\/div>\n<\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"wp-block-paragraph\"><em>This article is general information, not medical advice, and is not a substitute for care from a qualified healthcare professional. Speak to your doctor about your own situation.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>What 4BB, 3AA and 5BC actually mean, letter by letter, set beside live birth rates from two named studies, and what people who transferred graded embryos report.<\/p>\n","protected":false},"author":1,"featured_media":171,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","rank_math_title":"Good Quality 5 Day Embryo Blastocyst: What the Grade Means","rank_math_description":"A good quality 5 day embryo blastocyst is usually graded A or B on both cell layers. Higher grades do better in groups, but no grade predicts one transfer.","rank_math_focus_keyword":"good quality 5 day embryo blastocyst","rank_math_canonical_url":"","rank_math_breadcrumb_title":"","rank_math_facebook_title":"","rank_math_facebook_description":"","rank_math_facebook_image":"","rank_math_twitter_title":"","rank_math_twitter_description":"","rank_math_twitter_image":"","rank_math_pillar_content":"","rank_math_robots":[],"rank_math_advanced_robots":[]},"categories":[5],"tags":[],"class_list":["post-174","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-understanding-ivf"],"_links":{"self":[{"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/posts\/174","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/comments?post=174"}],"version-history":[{"count":8,"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/posts\/174\/revisions"}],"predecessor-version":[{"id":641,"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/posts\/174\/revisions\/641"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/media\/171"}],"wp:attachment":[{"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/media?parent=174"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/categories?post=174"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ivfprep.guide\/articles\/wp-json\/wp\/v2\/tags?post=174"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}