Developmental Surveillance and Milestones

❍ At a glance

• Developmental regression - loss of any previously acquired skill, at any age - is never benign without a clear cause. This is the most important red flag in developmental medicine and warrants urgent developmental paediatric referral.
• Parental instinct has strong positive predictive value. "Something feels off" from a parent who knows their child is a significant data point. Take it seriously.
• Other key red flags: no social smile by 8 weeks, no babble by 9 months, no joint attention by 12 months, no single words by 16 months, no two-word phrases by 24 months, no independent walking by 18 months.
• Waiting lists for paediatric developmental assessment are long across NZ. Early referral is essential. Early intervention services (Ministry of Education specialist support) can be engaged before a formal diagnosis and provide meaningful support during the wait.

❍ WCTO schedule and milestone overview

The Well Child Tamariki Ora (WCTO) programme provides funded structured developmental surveillance contacts from birth to age 5, delivered primarily by Plunket nurses, community nurses, and GPs.¹ Core contacts occur at: 3-5 days, 4-6 weeks (GP), 3-12 months (multiple Plunket contacts), and 15 months, 2 years, 3.5 years, 4-5 years. The B4 School Check at age 4 specifically includes the Ages and Stages Questionnaire (ASQ-3) and vision and hearing screening. Each contact covers growth monitoring (WHO growth charts), developmental screening across domains, immunisation review, and parental mental health assessment.

Key milestones by domain. Social and communication: social smile by 6-8 weeks; babble by 4-6 months; waves bye-bye by 9-10 months; first words (3-5 meaningful) by 12-15 months; two-word phrases by 18-24 months; short sentences by 2-3 years; understood by strangers approximately 75% of the time by age 3. Gross motor: head control by 3-4 months; sits unsupported by 7-9 months; walks independently by 9-15 months. Fine motor: pincer grip by 9-10 months; stacks blocks by 15 months; draws a circle by 3 years.

❍ Red flags, investigation, and ASD referral

Red flags warranting prompt developmental paediatric referral: developmental regression (any skill loss at any age); no social smile by 8 weeks; no babble by 9 months; no joint attention (pointing, showing, sharing gaze) by 12 months; no single words by 16 months; no two-word spontaneous phrases by 24 months; any loss of language or social skills at any age; no independent walking by 18 months; parental concern about possible ASD at any age.

Investigation: formal audiological assessment for any child with language delay or parental concern about hearing - glue ear (OME) is a treatable cause of apparent language delay and should be actively excluded. Routine blood tests, MRI, and metabolic screening are not required in uncomplicated developmental delay. A paediatrician will often arrange chromosomal microarray in a child with global developmental delay; thyroid function and FBC are reasonable baseline tests in a child with global delay presenting to the GP without prior workup.

For suspected ASD: in NZ, diagnosis requires multidisciplinary team assessment. The M-CHAT-R (18-24 months) can support the referral decision but is not diagnostic. The GP referral letter should document the specific behaviours of concern, their duration, and the settings in which they occur.

❍ NZ referral pathways

Referral for developmental assessment typically goes to: community paediatrics (developmental paediatrician), child development teams (in larger centres), or directly to speech-language therapy for isolated communication concerns. Waiting lists for paediatric developmental assessment are long across NZ; early referral is essential. Early intervention services (Ministry of Education specialist support) can be engaged before a formal diagnosis and provide meaningful support during the wait - document referral to these services in the clinical notes.