# When to worry about Rett syndrome at 6–9 months

Canonical: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-6-to-9-month-old-might-have-rett-syndrome
Publisher: Pinnacle Blooms Network / Bharath Healthcare Laboratories Private Limited

Rett syndrome is rare and seldom identifiable at 6–9 months, when most affected babies still meet early milestones. Its hallmark is a later regression — loss of skills, usually clear after 12–18 months. At this age, track the skills your baby has gained and share any genuine loss with a clinician rather than hunting for a label.

*If you've been searching milestones at 2am, worried that your baby might have Rett syndrome — let's bring you some calm and some clear facts.*

## In short
Rett syndrome is rare, and between 6 and 9 months most babies who later develop it are still meeting their early milestones — so this is usually too early to identify it with confidence. The hallmark of Rett syndrome is a *regression*: a period of typical early development followed by a loss of skills, most often becoming clear after 12–18 months. At your baby's age the wise stance is not to hunt for a label, but to gently track the skills your baby has gained and to share any genuine *loss* of those skills promptly with a clinician.

## What is actually worth watching at 6–9 months
At this age, the most meaningful thing is *progress* — is your baby gaining skills over the weeks? Reassuring signs of healthy development include reaching for and grasping toys, transferring objects between hands, babbling, responding to their name, and enjoying shared eye contact and smiles.

Gentle flags that deserve a developmental check (these point to *general* developmental review, not specifically Rett syndrome) include:

- **Loss of a skill** your baby clearly had — babbling that stops, or hands that no longer reach and grasp as before.
- **Hand use fading** — reduced purposeful use of the hands, or repetitive hand movements replacing reaching.
- **Slowing head growth** noted by your paediatrician at routine checks.
- **Persistently low muscle tone**, floppiness, or not gaining new movement skills over time.

A single quiet week, or one missed milestone, is rarely cause for alarm — babies develop in their own rhythm. It is a genuine *loss* of established skills, or a clear plateau over weeks, that warrants a prompt review.

## 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 checklist or a single observation. Because [Rett syndrome](/rett-syndrome) is a genetically based condition that a paediatrician investigates with specific testing, our role is to build your baby's developmental baseline, watch progress kindly, and support skills through [early intervention](/early-intervention-therapy) if anything is delayed. The goal is clarity and a path forward — not a frightening label at an age when one cannot yet be meaningful.

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

**Next step —** Trust your instincts and keep watching progress. [Book a developmental assessment](https://www.pinnacleblooms.org/enroll-autism-speech-aba-therapies-india) with a Pinnacle clinician if any skill your baby had clearly fades, or if your paediatrician flags head growth or tone.

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

## Sources
- WHO ICD-11: Rett syndrome (LD90.0): https://icd.who.int/browse11
- CDC developmental milestones — Learn the Signs, Act Early: https://www.cdc.gov/child-development
- AAP HealthyChildren — infant development: 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-6-9: https://pinnacleblooms.org/ask/lens/age/infant-6-9
- 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 should I worry that my 9-to-12-month-old might have Rett Syndrome?: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-9-to-12-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 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
- Early Signs of Rett Syndrome in a 6–9-Month-Old: https://pinnacleblooms.org/ask/what-are-the-early-signs-of-rett-syndrome-in-a-6-to-9-month-old
- When should I worry about Rett Syndrome in my 6-year-old?: https://pinnacleblooms.org/ask/when-should-i-worry-that-my-6-year-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
- 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