# When should I worry that my 9-to-12-month-old might have Rett Syndrome?

Canonical: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-9-to-12-month-old-might-have-rett-syndrome
Publisher: Pinnacle Blooms Network / Bharath Healthcare Laboratories Private Limited

At 9–12 months it is usually too early to confirm Rett syndrome, whose hallmark loss of hand use typically appears between 12 and 18 months. What warrants prompt review now is any genuine loss of skills a baby once had, slowing head growth, or a drop in engagement — none of which confirms Rett syndrome, but all of which deserve a developmental check.

*If you've noticed your baby seeming to pause or slip on skills they were reaching for, your watchful love is exactly the right instinct — let's make sense of it together.*

## In short
At 9–12 months it is usually too early to confirm [Rett syndrome](/rett-syndrome) — its most recognisable features, including the distinctive loss of purposeful hand use and the appearance of repetitive hand movements, typically emerge a little later, often between 12 and 18 months. What *does* deserve prompt attention at this age is any genuine *loss* of skills your baby had clearly gained, a stall in head growth, or a noticeable drop in alertness and engagement. None of these confirms Rett syndrome — but any one of them is a good reason for a developmental check now rather than waiting.

## What is worth noticing at 9–12 months
Rett syndrome is a rare, genetically based neurodevelopmental condition, recognised far more often in girls. In the first months babies often develop fairly typically, so the most meaningful early flag is *regression* — losing something already gained. Gentle things to observe:

- **Hand use** — your baby was reaching, grasping or transferring toys, and this fades or is replaced by repetitive hand-to-mouth or wringing movements.
- **Engagement** — less eye contact, smiling or babbling than before, or seeming to "switch off".
- **Head growth** — your paediatrician noticing head circumference slowing across visits.
- **Movement** — losing steadiness in sitting, or unusual stiffness or floppiness.

Most babies who seem briefly behind are simply moving at their own pace — but a real *loss* of established skills, in any child, is always worth checking sooner rather than later. It is the loss, not a slow start, that matters most.

## The Pinnacle way
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 online description or a single worry at home. Because Rett syndrome can involve a specific genetic change, our clinicians work first to build your baby's own developmental baseline and, where indicated, guide you toward the right medical and genetic review. If movement or daily skills are the concern, our [occupational therapy](https://www.pinnacleblooms.org/best-occupational-therapy-center-india-proven-improvement-rate) team can begin gentle, strengths-led support while answers are sought. The aim is clarity and a calm way forward — not a label.

## Trusted sources
WHO ICD-11 framework for developmental disorders; American Academy of Pediatrics developmental surveillance guidance; CDC developmental milestones and "Learn the Signs, Act Early" resources.

**Next step —** Trust what you've seen. [Book a developmental assessment](https://www.pinnacleblooms.org/enroll-autism-speech-aba-therapies-india) so any genuine loss of skills is reviewed promptly by a Pinnacle clinician.

This is general information, not a diagnosis — individual assessment and diagnosis require an appropriately qualified healthcare professional.

## Sources
- WHO ICD-11 framework for developmental disorders: https://icd.who.int/browse/2024-01/mms/en
- CDC developmental milestones — Learn the Signs, Act Early: https://www.cdc.gov/child-development
- AAP HealthyChildren infant development guidance: https://www.healthychildren.org/English/ages-stages/baby/Pages/default.aspx

## Connected topics and perspectives
- Conditions: https://pinnacleblooms.org/ask/conditions
- Parent: https://pinnacleblooms.org/ask/lens/stakeholder/parent
- Infant-9-12: https://pinnacleblooms.org/ask/lens/age/infant-9-12
- Context: https://pinnacleblooms.org/ask/lens/domain/context
- Concern: https://pinnacleblooms.org/ask/lens/intent/concern
- Screen: https://pinnacleblooms.org/ask/lens/lifecycle/screen
- Special Education: https://pinnacleblooms.org/ask/lens/route/special-education
- Early Clarity: https://pinnacleblooms.org/ask/lens/empowerment/early_clarity

## Related question paths

### Understand the subject
- How Rett Syndrome Affects a Child's Daily Life: https://pinnacleblooms.org/ask/how-does-rett-syndrome-affect-a-child-s-daily-life
- Is Rett Syndrome considered a disability?: https://pinnacleblooms.org/ask/is-rett-syndrome-considered-a-disability
- Is Rett Syndrome Genetic or Hereditary?: https://pinnacleblooms.org/ask/is-rett-syndrome-genetic-or-hereditary
- What are common myths about Rett Syndrome?: https://pinnacleblooms.org/ask/what-are-common-myths-about-rett-syndrome
- Types and Stages of Rett Syndrome: https://pinnacleblooms.org/ask/what-are-the-types-or-levels-of-rett-syndrome
- What causes Rett syndrome in children?: https://pinnacleblooms.org/ask/what-causes-rett-syndrome-in-children
- What is Rett Syndrome?: https://pinnacleblooms.org/ask/what-is-rett-syndrome
- What is Rett Syndrome, and what does it look like in early childhood?: https://pinnacleblooms.org/ask/what-is-rett-syndrome-and-what-does-it-look-like-in-early-childhood
- Conditions That Occur Alongside Rett Syndrome: https://pinnacleblooms.org/ask/what-other-conditions-often-occur-alongside-rett-syndrome
- Early Intervention Outcomes in Rett Syndrome (Under 7): https://pinnacleblooms.org/ask/what-does-current-research-show-about-early-intervention-outcomes-for-rett-syndrome-in-children-under-7
- What is Rett Syndrome, and its ICD-11 features in early childhood?: https://pinnacleblooms.org/ask/what-is-rett-syndrome-and-what-are-its-icd-11-features-in-early-childhood
- ICD-11 Classification of Rett Syndrome (LD90.0): https://pinnacleblooms.org/ask/what-is-the-icd-11-classification-for-rett-syndrome

### Recognise signs & concerns
- When to worry about Rett syndrome at 6–9 months: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-6-to-9-month-old-might-have-rett-syndrome
- Early Signs of Rett Syndrome in a 9-to-12-Month-Old: https://pinnacleblooms.org/ask/what-are-the-early-signs-of-rett-syndrome-in-a-9-to-12-month-old
- When should I worry about Rett Syndrome at 18–24 months?: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-18-to-24-month-old-might-have-rett-syndrome
- When to worry about Rett Syndrome at 12–18 months: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-12-to-18-month-old-might-have-rett-syndrome
- When should I worry about Rett Syndrome at 3–6 months?: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-3-to-6-month-old-might-have-rett-syndrome
- Early Signs of Rett Syndrome in Young Children: https://pinnacleblooms.org/ask/what-are-the-early-signs-of-rett-syndrome-in-young-children
- Can Rett Syndrome Be Cured?: https://pinnacleblooms.org/ask/can-rett-syndrome-be-cured
- Can Rett Syndrome Be Prevented?: https://pinnacleblooms.org/ask/can-rett-syndrome-be-prevented
- Rett Syndrome in Boys: https://pinnacleblooms.org/ask/do-boys-show-rett-syndrome-differently
- Do girls show Rett Syndrome differently?: https://pinnacleblooms.org/ask/do-girls-show-rett-syndrome-differently
- Should I be worried my child might have Rett Syndrome?: https://pinnacleblooms.org/ask/should-i-be-worried-my-child-might-have-rett-syndrome
- Early Signs of Rett Syndrome: https://pinnacleblooms.org/ask/what-are-the-early-signs-of-rett-syndrome

### Explore causes & influences
- Are boys more likely to have Rett Syndrome?: https://pinnacleblooms.org/ask/are-boys-more-likely-to-have-rett-syndrome
- Are girls more likely to have Rett Syndrome?: https://pinnacleblooms.org/ask/are-girls-more-likely-to-have-rett-syndrome
- What Causes Rett Syndrome in Young Children?: https://pinnacleblooms.org/ask/what-causes-rett-syndrome-in-young-children
- Early Intervention for Rett Syndrome, UNCRPD & the SDGs: https://pinnacleblooms.org/ask/how-does-early-intervention-for-rett-syndrome-advance-un-child-rights-uncrpd-and-the-sdgs
- Known contributing factors for Rett Syndrome: https://pinnacleblooms.org/ask/what-are-the-known-contributing-factors-for-rett-syndrome-in-early-childhood
- Cost-effectiveness of early therapy for Rett Syndrome in young children: https://pinnacleblooms.org/ask/what-is-the-cost-effectiveness-of-early-therapy-for-rett-syndrome-in-young-children
- Prevalence and Public-Health Burden of Rett Syndrome in India: https://pinnacleblooms.org/ask/what-is-the-prevalence-and-public-health-burden-of-rett-syndrome-among-young-children-in-india

### Understand assessment
- How AbilityScore Tracks Progress in a Child with Rett Syndrome: https://pinnacleblooms.org/ask/how-does-abilityscore-track-progress-in-a-child-with-rett-syndrome
- How Rett Syndrome Is Assessed in a Young Child: https://pinnacleblooms.org/ask/how-is-rett-syndrome-assessed-in-a-young-child
- How Rett Syndrome Is Assessed in Children Under 7: https://pinnacleblooms.org/ask/how-is-rett-syndrome-assessed-in-children-under-7
- What an AbilityScore® of 0–100 means for a child with Rett Syndrome: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-0-100-mean-for-a-child-with-rett-syndrome
- What does an AbilityScore of 100–200 mean for a child with Rett Syndrome?: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-100-200-mean-for-a-child-with-rett-syndrome
- What does an AbilityScore of 200–300 mean for a child with Rett Syndrome?: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-200-300-mean-for-a-child-with-rett-syndrome
- AbilityScore 300–400 in Rett Syndrome: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-300-400-mean-for-a-child-with-rett-syndrome
- What an AbilityScore of 400–500 Means in Rett Syndrome: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-400-500-mean-for-a-child-with-rett-syndrome
- What does an AbilityScore of 500–600 mean for a child with Rett Syndrome?: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-500-600-mean-for-a-child-with-rett-syndrome
- What does an AbilityScore of 600–700 mean for a child with Rett Syndrome?: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-600-700-mean-for-a-child-with-rett-syndrome
- What an AbilityScore of 700–800 Means for a Child with Rett Syndrome: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-700-800-mean-for-a-child-with-rett-syndrome
- What an AbilityScore of 800–900 Means for a Child with Rett Syndrome: https://pinnacleblooms.org/ask/what-does-an-abilityscore-of-800-900-mean-for-a-child-with-rett-syndrome

### Explore therapy & support
- Can a Child with Rett Syndrome Attend a Mainstream School?: https://pinnacleblooms.org/ask/can-a-child-with-rett-syndrome-attend-a-mainstream-school
- Can a Child with Rett Syndrome Attend a Regular School?: https://pinnacleblooms.org/ask/can-a-child-with-rett-syndrome-attend-a-regular-school
- Can a Child with Rett Syndrome Live Independently?: https://pinnacleblooms.org/ask/can-a-child-with-rett-syndrome-grow-up-to-live-independently
- How is Rett Syndrome diagnosed in a child?: https://pinnacleblooms.org/ask/how-is-rett-syndrome-diagnosed-in-a-child
- How is Rett Syndrome supported through therapy?: https://pinnacleblooms.org/ask/how-is-rett-syndrome-supported-through-therapy
- Rett Syndrome AbilityScore®: What to Do Next: https://pinnacleblooms.org/ask/my-child-with-rett-syndrome-has-an-abilityscore-of-0-100-what-should-we-do-next
- Rett Syndrome with an AbilityScore of 100–200: your next step: https://pinnacleblooms.org/ask/my-child-with-rett-syndrome-has-an-abilityscore-of-100-200-what-should-we-do-next
- Rett Syndrome: AbilityScore 200–300 — what to do next: https://pinnacleblooms.org/ask/my-child-with-rett-syndrome-has-an-abilityscore-of-200-300-what-should-we-do-next
- Rett Syndrome: AbilityScore 300–400 — what to do next: https://pinnacleblooms.org/ask/my-child-with-rett-syndrome-has-an-abilityscore-of-300-400-what-should-we-do-next
- Rett Syndrome with an AbilityScore of 400–500: what to do next: https://pinnacleblooms.org/ask/my-child-with-rett-syndrome-has-an-abilityscore-of-400-500-what-should-we-do-next
- Rett Syndrome and an AbilityScore of 500–600: What To Do Next: https://pinnacleblooms.org/ask/my-child-with-rett-syndrome-has-an-abilityscore-of-500-600-what-should-we-do-next
- Rett Syndrome AbilityScore 600–700: What To Do Next: https://pinnacleblooms.org/ask/my-child-with-rett-syndrome-has-an-abilityscore-of-600-700-what-should-we-do-next

### At home & in everyday life
- How can I support my child with Rett Syndrome at home?: https://pinnacleblooms.org/ask/how-can-i-support-my-child-with-rett-syndrome-at-home