{"h1":"When to worry about Rett Syndrome at 12–18 months","faq":[{"a":"Usually not. The hallmark of Rett Syndrome is regression — losing skills your daughter had already mastered, such as purposeful hand use or early words — rather than simply being a little late to reach one milestone. Many children have brief plateaus during illness or growth spurts. It is a clear loss of skills, often with repetitive hand movements, that should prompt a prompt review.","q":"Is a single delayed milestone a sign of Rett Syndrome?"},{"a":"It almost always affects girls. It is a rare genetic condition, and the classic pattern is typical early development followed by a slowing or loss of skills, most often between 6 and 18 months. If you notice your daughter going backwards on skills, see your paediatrician promptly.","q":"Does Rett Syndrome only affect girls?"},{"a":"No. Rett Syndrome has a genetic basis and is confirmed through medical assessment and testing arranged by a doctor, alongside a clinical developmental evaluation. No online form or checklist can diagnose it. Developmental measurement supports care planning; diagnosis requires an appropriately qualified healthcare professional. under qualified clinician care.","q":"Can you diagnose Rett Syndrome from a checklist?"}],"lang":"en","slug":"when-should-i-worry-that-my-12-to-18-month-old-might-have-rett-syndrome","title":"When to worry about Rett Syndrome at 12–18 months","entity":{"key":"rett","kind":"condition","name":"Rett Syndrome","slug":"rett-syndrome"},"lenses":[{"kind":"stakeholder","label":"Parent","value":"parent"},{"kind":"age","label":"Toddler-12-18","value":"toddler-12-18"},{"kind":"domain","label":"Context","value":"context"},{"kind":"intent","label":"Concern","value":"concern"},{"kind":"lifecycle","label":"Screen","value":"screen"},{"kind":"route","label":"Special-Education","value":"special-education"},{"kind":"empowerment","label":"Early Clarity","value":"early_clarity"}],"parent":{"key":"conditions","label":"Conditions"},"related":[{"lang":"en","slug":"when-should-i-worry-that-my-9-to-12-month-old-might-have-rett-syndrome","title":"When should I worry that my 9-to-12-month-old might have Rett Syndrome?"},{"lang":"en","slug":"when-should-i-worry-that-my-4-year-old-might-have-rett-syndrome","title":"When should I worry that my 4-year-old might have Rett Syndrome?"},{"lang":"en","slug":"when-should-i-worry-that-my-2-year-old-might-have-rett-syndrome","title":"When should I worry that my 2-year-old might have Rett Syndrome?"},{"lang":"en","slug":"when-should-i-worry-that-my-18-to-24-month-old-might-have-rett-syndrome","title":"When should I worry about Rett Syndrome at 18–24 months?"},{"lang":"en","slug":"what-are-the-early-signs-of-rett-syndrome-in-a-18-to-24-month-old","title":"Early Signs of Rett Syndrome in an 18-to-24-Month-Old"},{"lang":"en","slug":"what-are-the-early-signs-of-rett-syndrome-in-a-12-to-18-month-old","title":"Early Signs of Rett Syndrome at 12–18 Months"}],"summary":"Rett Syndrome is rare and almost always affects girls, with typical early development followed by a slowing or loss of skills, usually between 6 and 18 months. In the 12–18 month window the signal to act on is regression — losing hand skills or words she once had, repetitive hand movements, slowing head growth or new unsteadiness — not a single delayed milestone. Because it has a genetic basis, any suspected loss of skills warrants a prompt paediatric and developmental review. A diagnosis is formed only at a Pinnacle centre under clinician care, never from a checklist.","answer_md":"*If your little girl seemed to be growing beautifully and you've now noticed something has shifted, your watchfulness is loving and wise — let's make sense of it together.*\n\n## In short\nRett Syndrome ([ICD-11 LD90.0](/rett-syndrome)) is a rare genetic condition that almost always affects girls. Classically, development looks typical for the first 6–18 months, and then a child may slow down, plateau, or lose skills she had already gained — particularly purposeful use of the hands and emerging words. So in the 12–18 month window, the signal to act on is not a single milestone delay but a clear *regression* — a loss of skills she once had. This is a concern to have gently checked, never a diagnosis you should reach at home.\n\n## What would genuinely warrant a check\nIn this age band, the patterns clinicians take seriously are changes from your child's *own* earlier ability:\n\n- **Loss of purposeful hand use** — she used to reach, grasp or point, and now seems unable to\n- **Repetitive hand movements** — wringing, washing, tapping, squeezing or hand-to-mouth movements that replace useful hand skills\n- **Loss of babble or early words** she had previously used\n- **Slowing head growth** — your doctor may notice this on the growth chart\n- **New unsteadiness** in sitting or walking, or walking that doesn't emerge as expected\n- **Reduced eye contact or social engagement** after a period of being connected\n\nA single late milestone, in isolation, is usually *not* this. It is the picture of **regression — going backwards on skills already mastered** — that should prompt a prompt medical and developmental review.\n\n## When and where to seek help\nBecause Rett Syndrome has a genetic basis (often involving the MECP2 gene) and can be confirmed with medical testing, any suspected loss of skills deserves a **prompt paediatric and developmental review**, not a wait-and-see approach. Early review also rules in or out the many gentler explanations for a temporary plateau — illness, a growth spurt, or simply a child's own pace. Your paediatrician can arrange the right medical assessment alongside a developmental check.\n\n## The Pinnacle way\nA 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 online form or a checklist. Our clinicians map your daughter's whole developmental story, coordinate with medical testing where needed, and build supportive, strengths-based [occupational therapy](https://www.pinnacleblooms.org/best-occupational-therapy-center-india-proven-improvement-rate) and communication plans that protect her hand function, mobility and connection. Across 70+ centres and 25 million+ therapy sessions, families find a calm, expert team beside them from the very first question.\n\n## Trusted sources\nWHO ICD-11 (LD90.0, Rett Syndrome); American Academy of Pediatrics developmental surveillance guidance (healthychildren.org); WHO Nurturing Care Framework on early development.\n\n**Next step —** If you've noticed your daughter losing skills she once had, see your paediatrician promptly and [book a developmental check](https://www.pinnacleblooms.org/enroll-autism-speech-aba-therapies-india) with a Pinnacle clinician.\n\nThis is general information, not a diagnosis — individual assessment and diagnosis require an appropriately qualified healthcare professional.","canonical":"https://pinnacleblooms.org/ask/when-should-i-worry-that-my-12-to-18-month-old-might-have-rett-syndrome","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/when-should-i-worry-that-my-12-to-18-month-old-might-have-rett-syndrome","lang":"en","indexable":true},{"href":"https://pinnacleblooms.org/ask/when-should-i-worry-that-my-12-to-18-month-old-might-have-rett-syndrome-te","lang":"te","indexable":true}],"dimensions":[{"key":"conditions","label":"Conditions"}],"meta_title":"Rett Syndrome Signs at 12–18 Months","meta_robots":"index, follow, max-image-preview:large","everyday_tip":"Keep a simple note or short videos of what your daughter can do this month — words, pointing, how she holds a toy. If a skill she had clearly disappears rather than just pausing, that record helps your doctor see the pattern quickly.","published_at":"2026-06-10T10:58:00.048774+00:00","reading_paths":[{"key":"understand","items":[{"lang":"en","slug":"how-does-rett-syndrome-affect-a-child-s-daily-life","title":"How Rett Syndrome Affects a Child's Daily Life","reason":"Same topic"},{"lang":"en","slug":"is-rett-syndrome-considered-a-disability","title":"Is Rett Syndrome considered a disability?","reason":"Same topic"},{"lang":"en","slug":"is-rett-syndrome-genetic-or-hereditary","title":"Is Rett Syndrome Genetic or Hereditary?","reason":"Same topic"},{"lang":"en","slug":"what-are-common-myths-about-rett-syndrome","title":"What are common myths about Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"what-are-the-types-or-levels-of-rett-syndrome","title":"Types and Stages of Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"what-causes-rett-syndrome-in-children","title":"What causes 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A single late milestone alone is usually not this; it is the picture of going backwards that warrants a prompt paediatric review.","authority_links":[{"url":"https://icd.who.int/","code":"LD90.0","label":"WHO ICD-11: Rett Syndrome"},{"url":"https://www.healthychildren.org/","label":"AAP — developmental surveillance (healthychildren.org)"},{"url":"https://nurturing-care.org/","label":"WHO Nurturing Care Framework"}],"last_reviewed_at":"2026-06-10T10:58:00.048774+00:00","meta_description":"Worried about Rett Syndrome in your 12–18 month old? Learn the regression signs that warrant a prompt check — and the reassuring context every parent needs","related_materials":[],"related_techniques":[]}