{"id":60614,"date":"2015-06-10T08:31:45","date_gmt":"2015-06-10T06:31:45","guid":{"rendered":"https:\/\/wpcalc.com\/?p=60614"},"modified":"2026-09-28T13:48:42","modified_gmt":"2026-09-28T10:48:42","slug":"child-gender-updating-blood","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/pregnancy-baby\/child-gender-updating-blood\/","title":{"rendered":"Child Gender by Blood Renewal"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Baby Gender Predictor Based on Blood Renewal<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"60614\" data-favorite-title=\"Child Gender by Blood Renewal\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/child-gender-updating-blood\/\" data-favorite-excerpt=\"Enter both parents\u2019 birth dates and a conception date to see a traditional blood-renewal prediction. The result is for entertainment and cannot determine a baby\u2019s sex.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-pacifier\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/child-gender-updating-blood\/\" method=\"POST\" class=\"calculator\" id=\"calculator-60614\" data-post=\"60614\"><fieldset class=\"fieldset-input is-1\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Date of birth of the father<\/label><input type=\"date\" name=\"date_of_birth_of_the_father\" id=\"field-1\" step=\"any\" value=\"1996-11-11\"\/><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">Date of birth of the mother<\/label><input type=\"date\" name=\"date_of_birth_of_the_mother\" id=\"field-2\" step=\"any\" value=\"1998-11-11\"\/><\/div><div class=\"field\" id=\"input-3\"><label for=\"field-3\">Conception date<\/label><input type=\"date\" name=\"conception_date\" id=\"field-3\" step=\"any\" value=\"2026-11-11\"\/><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"60614\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Your Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>The sex of the child<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-2\"><span class=\"field-title\"><span>Last update of father\u2019s blood<\/span><\/span><span class=\"field-value\" id=\"result-2\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-3\"><span class=\"field-title\"><span>Last update of mater&#039;s blood<\/span><\/span><span class=\"field-value\" id=\"result-3\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"60614\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">12<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">8<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">4<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">16<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Child Gender by Blood Renewal Formula<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[k_f=\\left\\lfloor\\frac{Y_c-Y_f}{4}\\right\\rfloor,\\qquad k_m=\\left\\lfloor\\frac{Y_c-Y_m}{3}\\right\\rfloor \\\\ U_f=B_f+4k_f\\text{ calendar years},\\qquad U_m=B_m+3k_m\\text{ calendar years}\\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(B_f\\) and \\(B_m\\) \u2014 the father\u2019s and mother\u2019s birth dates.<\/li>\n<li>\\(Y_f\\), \\(Y_m\\), and \\(Y_c\\) \u2014 the calendar years of the father\u2019s birth, mother\u2019s birth, and conception.<\/li>\n<li>\\(U_f\\) and \\(U_m\\) \u2014 the calculated dates of the parents\u2019 most recent theoretical blood \u201cupdates.\u201d<\/li>\n<\/ul>\n<p>The calculator advances the father\u2019s birth date in four-year steps and the mother\u2019s in three-year steps, then compares the resulting dates. It displays \u201cMale\u201d if the father\u2019s date is later; otherwise, it displays \u201cFemale,\u201d including when the dates are equal. This is a traditional prediction rule, not a biological formula.<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Child Gender by Blood Renewal \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> the father was born on September 28, 1996, the mother on September 28, 1998, and the estimated conception date is September 28, 2026.<\/p>\n<p>\\[k_f=\\frac{2026-1996}{4}\\text{ rounded down}=7,\\qquad k_m=\\frac{2026-1998}{3}\\text{ rounded down}=9\\]<\/p>\n<p>\\[U_f=\\text{September 28, 2024},\\qquad U_m=\\text{September 28, 2025}\\]<\/p>\n<p><strong>Result:<\/strong> the mother\u2019s calculated update date is later, so the calculator displays \u201cFemale.\u201d This is only the method\u2019s guess; it does not establish the child\u2019s sex.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Enter the father\u2019s birth date in <strong>Date of birth of the father<\/strong>.<\/li>\n<li>Enter the mother\u2019s birth date in <strong>Date of birth of the mother<\/strong>.<\/li>\n<li>Enter the estimated <strong>Conception date<\/strong>. If you are unsure of it, a <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/date-of-conception\/\">date of conception calculator<\/a> may help you estimate one.<\/li>\n<li>Read <strong>The sex of the child<\/strong> as the method\u2019s prediction. Check <strong>Last update of father\u2019s blood<\/strong> and <strong>Last update of mater\u2019s blood<\/strong> to see which calculated date is later.<\/li>\n<\/ol>\n<p>The fields may initially contain dates based on the day you open the page. Replace them with the dates you intend to compare. The worked example uses September 28, 2026, as its conception date, so its result may differ from the prefilled result on another day.<\/p>\n<h2>What blood renewal means in this calculation<\/h2>\n<p>The blood-renewal method is a folk prediction that assigns a four-year cycle to fathers and a three-year cycle to mothers. It calls the parent with the later calculated \u201cupdate\u201d the one with \u201cnewer blood,\u201d then predicts \u201cMale\u201d for the father or \u201cFemale\u201d for the mother. The dates in the results are theoretical cycle markers counted from each birth date, not dates of actual changes in anyone\u2019s blood.<\/p>\n<p>Blood cells are continually produced and replaced; the idea that a person\u2019s entire blood supply renews on a fixed three- or four-year schedule has no scientific basis. Nor is there evidence that the relative age of parents\u2019 blood predicts a baby\u2019s sex. A later update date should therefore be interpreted only as the reason this particular rule produced its answer, not as evidence about the pregnancy.<\/p>\n<p>Chromosomal sex is typically determined at fertilization by whether the sperm contributes an X or Y chromosome, though biological sex development can be more complex. Neither parent\u2019s birth date changes that process. If you would like to compare another traditional guessing method, the <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/chinese-baby-gender-calculator\/\">Chinese Baby Gender calculator<\/a> offers one; it is not medically reliable either.<\/p>\n<h2>Assumptions and limitations<\/h2>\n<ul>\n<li><strong>Use a plausible conception date.<\/strong> The calculator checks whether entries are valid dates, but it does not verify that conception occurred after both parents were born.<\/li>\n<li><strong>A cycle marker can fall after conception.<\/strong> The code advances cycles by comparing calendar years, not by checking whether the birthday has passed within the conception year. Near a cycle anniversary, a displayed \u201clast update\u201d may therefore be a future date.<\/li>\n<li><strong>Equal dates are not a special outcome.<\/strong> If both calculated dates match, this calculator displays \u201cFemale.\u201d An equal result does not indicate twins.<\/li>\n<li><strong>Displayed date formats can vary.<\/strong> Read the day and month carefully when checking the two update dates.<\/li>\n<\/ul>\n<p>For pregnancy planning, a <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/pregnancy-due-date\/\">pregnancy due date calculator<\/a> addresses a different question: it estimates timing, not the baby\u2019s sex. Discuss questions about prenatal testing and what a result can tell you with a qualified healthcare professional.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Enter both parents\u2019 birth dates and a conception date to see a traditional blood-renewal prediction. The result is for entertainment and cannot determine a baby\u2019s sex.<\/p>\n","protected":false},"author":70,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[45],"tags":[49],"class_list":["post-60614","post","type-post","status-publish","format-standard","hentry","category-pregnancy-baby","tag-baby-gender-prediction"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/60614","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/70"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=60614"}],"version-history":[{"count":3,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/60614\/revisions"}],"predecessor-version":[{"id":65374,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/60614\/revisions\/65374"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=60614"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=60614"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=60614"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}