Early Signs of Rett Syndrome in a 3-to-6-Month-Old

When a parent senses something in their baby's early months feels different, that gentle attentiveness is precious — and worth honouring with care, not alarm.

In short

In the first months, Rett Syndrome is usually very hard to spot — most babies with it develop seemingly typically until around 6–18 months, when skills may plateau or slip. Between 3 and 6 months, the earliest soft signs some parents later recall include reduced eye contact, lower muscle tone (a baby who feels a little 'floppy'), feeding difficulties, and being unusually calm or less engaged. None of these alone means Rett Syndrome — they are gentle reasons for a developmental check, not a diagnosis.

Gentle signs some parents notice

Connection and engagement

• Less eye contact or shared smiling than expected
• Seeming unusually placid, quiet or hard to engage in to-and-fro play

Body and movement

• Lower muscle tone — a baby who feels softer or 'floppy' when held
• Slightly slower head control or reaching for toys
• Less spontaneous hand use, or hands less often brought to the midline

Feeding and growth

• Feeding or sucking difficulties
• Head growth that begins to slow (head circumference is tracked at routine checks)

Importantly, the more recognisable features of Rett Syndrome — loss of purposeful hand skills, repetitive hand movements, and slowing head growth — typically emerge after 6 months, often between 6 and 18 months. So at 3–6 months the picture is usually subtle.

Why a calm, prompt check helps

Rett Syndrome (ICD-11 LD90.0) is a rare genetic condition, most often caused by changes in the MECP2 gene, and it is overwhelmingly diagnosed in girls. Because the early infancy signs are non-specific and overlap with many ordinary variations in development, the right step is never to self-diagnose but to share your observations with a clinician. Routine measuring of head circumference and developmental review can pick up early patterns, and genetic testing confirms the diagnosis when indicated. Early, gentle support helps every child — whatever the eventual answer.

The Pinnacle way

A clinical AbilityScore® and any diagnosis are formed only at a Pinnacle Blooms Network centre, under qualified clinician care — never from a checklist or a worried late-night search. Our team looks at the whole baby across tone, feeding, connection and growth to understand what is happening. Learn more about Rett Syndrome and how early occupational therapy can support your child's movement, hands and engagement.

Trusted sources

Guided by WHO and the ICD-11 framework for Rett Syndrome, the American Academy of Pediatrics and HealthyChildren.org on developmental monitoring and head-growth tracking, and CDC milestone guidance — all paraphrased here for parents.

Next step — book a calm, reassuring developmental check with our team on WhatsApp: +91 91001 81181, and let's understand your baby together.