{"h1":"WHO Windows of Achievement for Gross Motor Milestones (WHO-GMM)","faq":[{"a":"No. The WHO-GMM is a reference describing the normal age ranges in which healthy children reach six gross-motor milestones. It helps understand typical patterns and variation, but a diagnosis is never made from a chart — it requires a qualified clinician's structured assessment.","q":"Is the WHO-GMM a test that diagnoses motor delay?"},{"a":"Six gross-motor milestones: sitting without support, standing with assistance, hands-and-knees crawling, walking with assistance, standing alone and walking alone — each with its own broad, healthy age window.","q":"Which milestones does the WHO-GMM cover?"},{"a":"Not necessarily. The WHO study found that not every healthy child crawls in the classic way; some bottom-shuffle or move differently and still walk well. If you have concerns, a calm developmental review can offer reassurance or early support.","q":"My child skipped crawling — is that a problem?"}],"lang":"en","slug":"what-is-the-who-windows-of-achievement-for-gross-motor-milestones-who-gmm-and-what-does-it-assess","title":"What is the WHO Windows of Achievement for Gross Motor Milestones (WHO-GMM)?","entity":{"key":"who_gmm","kind":"instrument","name":"WHO Windows of Achievement for Gross Motor Milestones","slug":"who-gmm"},"lenses":[{"kind":"stakeholder","label":"Parent","value":"parent"},{"kind":"intent","label":"Definition","value":"definition"},{"kind":"lifecycle","label":"Measure","value":"measure"},{"kind":"route","label":"Screen","value":"screen"},{"kind":"empowerment","label":"Early Clarity","value":"early_clarity"}],"parent":{"key":"assessments","label":"Assessments"},"related":[{"lang":"en","slug":"how-do-i-check-if-my-child-s-motor-development-is-on-track","title":"How do I check if my child's motor development is on track?"},{"lang":"en","slug":"at-what-age-is-the-who-gmm-developmental-assessment-used-for-a-child","title":"At What Age Is the WHO-GMM Used for a Child?"},{"lang":"en","slug":"how-does-the-who-gmm-compare-with-the-abilityscore-developmental-assessment","title":"How does the WHO-GMM compare with the AbilityScore developmental assessment?"},{"lang":"en","slug":"what-are-the-key-motor-milestones-in-early-childhood","title":"Key motor milestones in early childhood"},{"lang":"en","slug":"should-my-child-have-a-who-gmm-assessment-and-what-does-it-involve","title":"Should My Child Have a WHO-GMM Assessment?"},{"lang":"en","slug":"when-is-the-who-gmm-indicated-and-what-are-its-strengths-and-limits-in-early-childhood","title":"When is the WHO-GMM indicated, and what are its strengths and limits?"}],"summary":"The WHO Windows of Achievement for Gross Motor Milestones (WHO-GMM) is a World Health Organization reference describing the typical age ranges in which healthy children worldwide reach six big-movement milestones: sitting without support, standing with assistance, hands-and-knees crawling, walking with assistance, standing alone and walking alone. It assesses when, not how well, these skills appear by giving a normal window of months for each rather than a fixed deadline, reflecting healthy variation. It is a population reference for understanding typical development, not a diagnostic test for an individual child.","answer_md":"*Six simple movement milestones, and the natural age ranges in which healthy children around the world reach them — that is the WHO Windows of Achievement.*\n\n## In short\nThe **WHO Windows of Achievement for Gross Motor Milestones (WHO-GMM)** is a research-based reference, published by the World Health Organization, that describes the typical age ranges in which healthy children reach six key gross-motor (big-movement) milestones. It assesses *when* — not *how well* — a child sits, stands and walks, by giving a normal *window* of months for each skill rather than a single fixed deadline. It is a guide for understanding healthy variation, not a diagnostic test.\n\n## What the WHO-GMM looks at\nThe WHO-GMM grew from a large multi-country study that followed healthy, well-nourished children across diverse settings, confirming that early motor development follows a remarkably similar pattern worldwide. It maps six milestones, each with its own age *window*:\n\n- **Sitting without support**\n- **Standing with assistance**\n- **Hands-and-knees crawling**\n- **Walking with assistance**\n- **Standing alone**\n- **Walking alone**\n\nThe gift of the *window* idea is reassurance: there is no single \"right\" month to walk or sit. Each milestone has a broad, healthy range, so a child who walks at 11 months and one who walks at 15 months can both be developing perfectly typically. The WHO-GMM also gently notes that not every child crawls in the classic way — some bottom-shuffle or move differently — and still reach walking well. It is a population reference for typical development, used to understand patterns, not to label an individual child.\n\n## When to seek a review\nWindows are wide, but they do have outer edges. Consider a developmental review if your child has clearly passed the upper end of a window without showing the skill — for example, not sitting independently or not walking by the ages your paediatrician flags — or if you notice your child losing a skill they once had, very stiff or very floppy movement, or strong one-sided preference in the early months. These are reasons to check in early, calmly, so that any helpful support can begin while development is most responsive.\n\n## The Pinnacle way\nThis is general information, not a diagnosis — a clinical [AbilityScore®](/ask/what-is-the-abilityscore-and-how-is-it-calculated) and any diagnosis are formed only at a Pinnacle Blooms Network centre, under qualified clinician care, never from an app or form. Our clinicians use references like the [WHO-GMM](/who-gmm) alongside structured assessment of your child's whole movement picture, and where helpful build an individualised plan that may draw on [occupational therapy](https://www.pinnacleblooms.org/best-occupational-therapy-center-india-proven-improvement-rate) and other supports.\n\n## Trusted sources\nWHO Multicentre Growth Reference Study on motor development milestones and their age windows; WHO Nurturing Care Framework on early childhood development; CDC and HealthyChildren guidance on gross-motor milestones and healthy variation.\n\n**Next step —** If you want to understand where your child sits within the WHO motor windows, book a gentle developmental review to map their movement strengths and start any helpful support early.","canonical":"https://pinnacleblooms.org/ask/what-is-the-who-windows-of-achievement-for-gross-motor-milestones-who-gmm-and-what-does-it-assess","editorial":{"reviewed_at":"2026-06-11T20:12:18.613642+00:00","reviewed_by":null,"developed_by":"SETU Consortium · Pinnacle Blooms Network"},"alternates":[{"href":"https://pinnacleblooms.org/ask/what-is-the-who-windows-of-achievement-for-gross-motor-milestones-who-gmm-and-what-does-it-assess","lang":"en","indexable":true}],"dimensions":[{"key":"assessments","label":"Assessments"}],"meta_title":"WHO-GMM: Gross Motor Milestone Windows","meta_robots":"index, follow, max-image-preview:large","everyday_tip":"Give plenty of supervised floor and tummy time and safe space to roll, reach, pull to stand and cruise along furniture — everyday play is how big-movement skills grow, so follow your child's pace rather than a fixed calendar.","published_at":"2026-06-10T14:16:00.221239+00:00","reading_paths":[{"key":"understand","items":[{"lang":"en","slug":"at-what-age-is-the-who-gmm-developmental-assessment-used-for-a-child","title":"At What Age Is the WHO-GMM Used for a Child?","reason":"Linked from this answer"}],"label":"Understand the subject","total":1},{"key":"signs","items":[{"lang":"en","slug":"what-are-the-key-motor-milestones-in-early-childhood","title":"Key motor milestones in early childhood","reason":"Linked from this answer"}],"label":"Recognise signs & concerns","total":1},{"key":"assess","items":[{"lang":"en","slug":"should-my-child-have-a-who-gmm-assessment-and-what-does-it-involve","title":"Should My Child Have a WHO-GMM Assessment?","reason":"Linked from this answer"},{"lang":"en","slug":"when-is-the-who-gmm-indicated-and-what-are-its-strengths-and-limits-in-early-childhood","title":"When is the WHO-GMM indicated, and what are its strengths and limits?","reason":"Linked from this answer"},{"lang":"en","slug":"how-does-the-who-gmm-compare-with-the-abilityscore-developmental-assessment","title":"How does the WHO-GMM compare with the AbilityScore developmental assessment?","reason":"Linked from this answer"}],"label":"Understand assessment","total":3},{"key":"therapy","items":[{"lang":"en","slug":"how-do-i-check-if-my-child-s-motor-development-is-on-track","title":"How do I check if my child's motor development is on track?","reason":"Linked from this answer"}],"label":"Explore therapy & support","total":1}],"what_to_watch":"Clearly passing the upper end of a milestone window without the skill (e.g. not sitting or not walking by the flagged ages), losing a skill once gained, very stiff or very floppy movement, or strong one-sided preference in the early months.","authority_links":[{"url":"https://www.who.int/tools/child-growth-standards","label":"WHO Child Growth Standards & motor development milestones"},{"url":"https://nurturing-care.org","label":"WHO Nurturing Care Framework for early childhood development"},{"url":"https://www.cdc.gov/child-development","label":"CDC developmental milestones guidance"}],"last_reviewed_at":"2026-06-10T14:16:00.221239+00:00","meta_description":"The WHO-GMM describes the normal age ranges in which healthy children sit, crawl, stand and walk — a guide to typical motor development, not a diagnosis.","related_materials":[],"related_techniques":[]}