Family doctor


Children's Health



This article provides a thorough overview of developmental stages in children. It looks at delays in children's development, the risk factors for delays, and what tests are used to assess a child's progress.

developmental delay


Most babies and children reach important milestones within the expected timeframes. But in some cases developmental delays can occur. It is important to recognise when a child may not be developing at an average pace. This article will help to explain normal developmental progress for adults and children, when to seek help, and what tests and investigations are necessary to establish any problem areas.

Benefits of early identification for at risk children:

Early developmental intervention and education helps to influence a young, malleable and responsive brain.

It helps to maximise a child's developmental potential; their functional abilities such as social communication, mobility and adaptive skills. It also helps to limit maladaptive functioning.

Parents can learn how their child is developing in relation to other children, tailor their expectations to what the child can achieve, and provide stimulation, and toys to match the child's readiness for the different milestones. This allows family members to think that they are doing all their can to assist the child, and to bolster the child's sense of being appreciated for who he or she is - an important preventative measure against further emotional disability.

Early intervention will provide preventive strategies for environmentally, and possibly biologically, at-risk children.

In some cases early diagnosis of a genetic disorder, metabolic or infectious disease can prevent further damage, or another child being born with the same disability.

Identification rates of developmental disabilities:


PREVALENCE (per 1000)



Mental retardation




Learning disability








Cerebral palsy




Visual impairment




Hearing impairment





More severe developmental delays come to parents and doctors attention earlier - this includes mental retardation, cerebral palsy and vision problems. These disabilities are usually diagnosed before a child starts school. However, less severe problems like learning difficulties and attention deficit hyperactivity disorder (ADHD), are usually identified in school age children.

Signs and symptoms of developmental delay:

  • The child may not be able to feed, sit, crawl, walk, talk, or be toilet trained.
  • The child may show a lack of responsiveness and fail to reach normal milestones within the expected timeframe.
  • Children who are blind or who have vision difficulties are likely to have delayed exploration skills and take longer to walk (18 to 24 months). Their first smile may be delayed. Language skills may be normal but there could be a delayed understanding of "I" and "you". They find it difficult to understand the properties of objects and shapes.
  • Deaf children are likely to have delayed language milestones.
  • There may be behavioural problems such as sleeping difficulties, poor social interactions, unusual dietary habits, self stimulation, and self mutilation.
  • "Dysmorphic"(unusual shape or appearance) features are often equated with mental retardation.


Doctors will look at the following factors when investigating concerns about developmental delays:

  • Biological risk - genetic risk factors or neonatal risk factors for intellectual handicap.
  • Environmental risk - maternal and family care, health care, nutrition, and limited opportunities for stimulation of normal development leading to delays in development.
  • Established risk - a diagnosed medical disorder either present at birth or arising afterwards which has a high risk of resulting in developmental delays.
  • Evaluation of the effects of possible emotional neglect or physical or sexual abuse.
  • Recognised neurological disorders - seizures, movement disorder, spasticity etc.
  • Effect of a chronic illness/organ dysfunction.

Warning signs of developmental delay:

  • "Good" baby
  • Late smiling
  • Delayed visual alertness
  • Late chewing/gagging
  • Persistent reciprocal kicking
  • Primitive reflexes
  • Persistent hand regard/mouthing/slobbering
  • Altered vocalisations (repeated and constant stimulus to elicit cry)
  • Voice quality guttural, piercing, shriek-like, high pitched, weak or thin
  • Delayed babble repertoire
  • Lack of interest and concentration
  • Aimless overactivity
  • Neuromuscular weakness
  • Blind or deaf
  • Drug effects
  • Emotional deprivation

The best predictors of development are skills relating to brain functioning, rather than reaching specific movement milestones within the expected timeframe.

Motor milestones are excellent indicators of movement skills, but correlate poorly with intellectual functioning.

Language and problem solving milestones in infancy provide the best insights into intellectual potential, and their evolution is independent of motor skills which may be obscured by physical disability.

Psychosocial abilities are critical to understand the whole child and in making a meaningful assessment about behaviour, but they do little in assessing motor and intellectual skills.

What is a delay?

A developmental delay is defined as absence of age specific developmental behaviours.

The following is a guideline by age and months of delay:



6 months

1.5 months

12 months

3 months

18 months

4 months

24 months

6 months

30 months

7 months


A delay in learning increases the risk for diagnosis of a specific mental disability or medical condition. These may include:

  • Mental Retardation
  • Cerebral Palsy
  • Pervasive Developmental Disorder/Autism
  • Blind or Deaf
  • Specific Developmental Disorder (language/speech disorder)
  • Attention Deficit Hyperactivity Disorder

A developmental delay becomes Mental Retardation after the age 3 years due to ability to provide more accurate tests; however, a diagnosis may be made earlier where there is a significant degree of impairment. (Moderate mental retardation suspected at 12 months, established by 2 years; mild mental retardation suspected at 2 years, established at 3 years). However, parents need to maintain hope, therefore continue to use delay, where there is potential for catch up.

Complicating factors:
  • Normal developmental spurts and lags.
  • Gender differences (girls earlier than boys and more rapid rate of development, except with some motor skills - onset of walking, and visuospatial skills i.e. jigsaw puzzles. Girls earlier with some social and communication skills. "Peak" spurt of speech and language around 18 to 24 months; for boys between 2 to 3 years).
  • Correction for prematurity - more relevant for motor development than language skills (correct up to approx. 18-24 months).

Risk factors

Prenatal maternal factors:
  • Previous miscarriage or stillbirth
  • Acute or chronic illness (e.g. HIV)
  • Poor nutrition
  • Hyperthermia
  • Use of drugs or alcohol
  • Toxaemia
  • Fetal movements
Perinatal factors:
  • Obstetric complications
  • Prematurity (less than 33 weeks)
  • Low birth weight (less than 1500g)
  • Multiple birth
Neonatal factors:
  • Neurological events (e.g. seizures)
  • Sepsis or meningitis
  • Severe jaundice
  • Hypoxia due to breathing difficulties
  • Neonatal intensive care unit admission of more than 5 days
Postnatal factors:
  • Seizures
  • Sepsis or meningitis
  • Recurrent ear infections
  • Poor feeding
  • Poor growth
  • Exposure to lead or other toxins
Factors in the family history:
  • Consanguinity
  • Developmental delay (difficulty walking, talking, learning)
  • Neurological disease (muscle weakness, seizures, migraines)
  • Deafness/Blindness
  • Cardiomyopathy
  • Known chromosomal abnormalities
Factors in the social history:
  • History of abuse or neglect
  • Limited financial or social support
  • Lack of food, clothing or shelter
  • Teenage parent
  • Single parent
  • Mentally retarded parent
  • Stressful life events (e.g. divorce, death, or unemployment of parent)
  • Substance abuse in the home
  • Parental chronic illness limiting caregiving ability
Physical characteristics of mental retardation:

Intellectually handicapped children may show some unusual physical signs indicative of mental retardation, these may include a small or large head circumference, a short stature, obesity (Prader-Willi Syndrome), excessive height, limb deformities, unusually shaped ears or placement, and skeletal abnormalities.

Developmental evaluation

Various screening techniques are used to assess the level of intellectual functioning for babies and children. Some of these include:


4 months

Tries to reach cube, but overshoots and misses

5 months

Able to grasp voluntarily. Uses both hands

6 months

More mature grasp. Drops one cube when another is given

7 months

Holds cube in one hand. Bangs cube on table. Transfers, and retains one when another is given

8 months

Reaches persistently for cube out of reach

9 months

Matches cubes

10 months

Release beginning. Holds cube to examiner but will not release it

11 months

Begins to put cubes in and out of container

12 months

Beginning to cast objects onto the floor

15 months

Tower of two. Holds two cubes in one hand

18 months

Tower of three or four

Common objects (penny, shoe, pencil, ball):

18 months

Names one

2 years

Names two to five

2.6 years

Names five


3 years

Names one

4 years

Names two or three

5 years

Names four


15 months

Imitates scribble or scribbles spontaneously.

18 months

Makes stroke imitatively.

2 years

Imitates vertical and circular stroke.

2.6 years

Two or more strokes for cross. Imitates horizontal stroke.

3 years

Copies circle. Imitates cross. Draws a man.

4 years

Copies cross

4.6 years

Copies square

5 years

Copies triangle

6 years

Copies diamond

Risk factors for developmental delay identified on developmental assessment:

Motor skills



4.5 months

Does not pull up to sit

5 months

Does not roll over

7-8 months

Does not sit without support

9-10 months

Does not stand while holding on

15 months

Not walking

2 years

Not climbing up or down stairs

2.5 years

Not jumping with both feet

3 years

Unable to stand on one foot momentarily

4 years

Not hopping

5 years

Unable to walk a straight line back and forth or balance on one foot


5-6 months

Not babbling

8-9 months

Not saying "da" or "ba"

10-11 months

Not saying "dada" or "baba"

18 months

Has less than three words with meaning

2 years

No two word phrases or repetition of phrases

2.6 years

Not using at least one personal pronoun

3.6 years

Speech only half understandable

4 years

Does not understand prepositions

5 years

Not using proper syntax in short sentences

Mental skills

2-3 months

Not alert to mother

6-7 months

Not searching for dropped object

8-9 months

No interest in peek-a-boo

12 months

Does not search for hidden object

15-18 months

No interest in cause and effect games

2 years

Does not categorise similarities (e.g. animals vs. vehicles)

3 years

Does not know own full name

4 years

Cannot pick shorter or longer of two lines

4.6 years

Cannot count sequentially

5 years

Does not know colours or any letters

5.6 years

Does not know own birthday or address


3 months

Not smiling socially

6-8 months

Not laughing in playful situations

1 year

Hard to console, stiffens when approached

2 years

Kicks, bites, screams easily without provocation. Rocks back and forth in crib. No eye contact or engagement with other children or adults

3-5 years

In constant motion, resists discipline, does not play with other children

Obstacles to identifying at risk children

Clinical evaluation by doctors only identifies about half the children in need due to some of the following factors:

  • The natural wide variation among children makes it easy to ignore a subtle finding.
  • The potential to overlook one area of development. All streams of development need to be assessed.
  • Parents and doctors may find it difficult to discuss their fears and be unwilling to confront the painful reality that the child may have a developmental problem. Doctors need to use the phrase: "The child will grow out of it" with caution.

Early intervention and treatment

What works?
  • Multidisciplinary teams to work with the parents and child
  • Whole development of the child
  • Home-based programmes for preschool children
  • Parental involvement
  • Increasing skills for parents
  • Early intervention

Protective factors for children with developmental delay

There are several recognised factors which may help limit problems linked to slow development. These include:

  • The child displays physical robustness and vigour, an easy temperament, and intelligence.
  • There are affectionate ties and socialisation practises within the family that encourage trust, autonomy, and initiative.
  • External support systems which reinforce competence and provide children with a positive set of values.
  • A sense of self esteem and confidence.
  • A belief in one's own self-sufficiency and ability to deal with change
  • A range of social problem solving approaches

See also:

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