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* This is the Professional Version. *

Childhood Development

By Evan G. Graber, DO, Sydney Kimmel Medical College;Nemours/Alfred I. duPont Hospital for Children

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Development is often divided into specific domains, such as gross motor, fine motor, language, cognition, and social/emotional growth. These designations are useful, but substantial overlap exists. Studies have established average ages at which specific milestones are reached, as well as ranges of normality. In a normal child, progress within the different domains varies, as in the toddler who walks late but speaks in sentences early (see Table: Developmental Milestones*).

Developmental Milestones*




Sleeps much of the time


Clears airway

Responds with crying to discomforts and intrusions

4 wk

Brings hands toward eyes and mouth

Moves head from side to side when lying on stomach

Eyes follow an object moved in an arc about 15 cm above face to the midline

Responds to a noise in some way (eg, startling, crying, quieting)

May turn toward familiar sounds and voices

Focuses on a face

6 wk

Regards objects in the line of vision

Begins to smile when spoken to

Lies flat on abdomen

Head lags when pulled to a sitting position

3 mo

Holds head steady on sitting

Raises head 45° when lying on stomach

Opens and shuts hands

Pushes down when feet are placed on a flat surface

Swings at and reaches for dangling toys

Follows an object moved in an arc above face from one side to the other

Watches faces intently

Smiles at sound of caretaker’s voice

Vocalizes sounds

5–6 mo

Holds head steady when upright

Sits with support

Rolls over, usually from stomach to back

Reaches for objects

Recognizes people at a distance

Listens intently to human voices

Smiles spontaneously

Squeals in delight

Babbles to toys

7 mo

Sits without support

Bears some weight on legs when held upright

Transfers objects from hand to hand

Holds own bottle

Looks for dropped object

Responds to own name

Responds to being told “no”

Combines vowels and consonants to babble

Moves body with excitement in anticipation of playing

Plays peekaboo

9 mo

Sits well

Crawls or creeps on hands and knees

Pulls self up to standing position

Works to get a toy that is out of reach; objects if toy is taken away

Gets into a sitting position from stomach

Stands holding on to someone or something

Says "mama" or "dada" indiscriminately

12 mo

Walks by holding furniture (“cruising”) or others' hands

May walk 1 or 2 steps without support

Stands for a few moments at a time

Says "Dada" and "Mama" to the appropriate person

Drinks from a cup

Claps hands and waves bye-bye

Speaks several words

18 mo

Walks well

Can climb stairs holding on

Draws a vertical stroke

Makes a tower of 4 cubes

Turns several book pages at a time

Speaks about 10 words

Pulls toys on strings

Partially feeds self

2–2½ yr

Runs well/with coordination

Climbs on furniture


Climbs up and down stairs without help

Handles a spoon well

Turns single book pages

Makes a tower of 7 cubes

Opens doors

Scribbles in a circular pattern

Puts on simple clothing

Makes 2- or 3-word sentences

Verbalizes toilet needs

3 yr

Mature gait in walking

Rides a tricycle

Favors using one hand over the other

Copies a circle

Dresses well except for buttons and laces

Counts to 10 and uses plurals

Recognizes at least 3 colors

Questions constantly

Feeds self well

Can take care of toilet needs (in about half of children)

4 yr

Alternates feet going up and down stairs

Throws a ball overhand

Hops on 1 foot

Copies a cross

Dresses self

Washes hands and face

5 yr


Catches a bounced ball

Copies a triangle

Draws a person in 6 parts

Knows 4 colors

Dresses and undresses without help

6 yr

Walks along a straight line from heel to toe

Writes name

*The sequence is fairly consistent, but the timing of milestones varies; times above represent median values.

Environmental influences, ranging from nutrition to stimulation and from the impact of disease to the effects of psychologic factors, interact with genetic factors to determine the pace and pattern of development.

Assessment of development occurs constantly as parents, school personnel, and clinicians evaluate children. Many tools are available for monitoring development more specifically. The Denver Developmental Screening Test II facilitates evaluation in several domains. The scoring sheet indicates the average ages for achieving certain milestones and nicely shows the critical concept of a range of normality. Other tools can also be used (see Table: Developmental Milestones*).

Motor Development

Motor development includes fine motor (eg, picking up small objects, drawing) and gross motor (eg, walking, climbing stairs) skills. It is a continuous process that depends on familial patterns, environmental factors (eg, when activity is limited by prolonged illness), and specific disorders (eg, cerebral palsy, intellectual disability, muscular dystrophy). Children typically begin to walk at 12 mo, can climb stairs holding on at 18 mo, and run well at 2 yr, but the age at which these milestones are achieved by normal children varies widely. Motor development cannot be significantly accelerated by applying increased stimulation.

Language Development

The ability to understand language precedes the ability to speak; children with few words usually can understand a great deal. Although delays in expressive speech are typically not accompanied by other developmental delays, all children with excessive language delays should be evaluated for the presence of other delays in development. Children who have delays in both receptive and expressive speech more often have additional developmental problems. Evaluation of any delay should start with an assessment of hearing. Most children who experience speech delay have normal intelligence. In contrast, children with accelerated speech development are often of above-average intelligence.

Speech progresses from the utterance of vowel sounds (cooing) to the introduction of syllables that start with consonants (ba-ba-ba). Most children can say “Dada” and “Mama” specifically by 12 mo, use several words by 18 mo, and form 2- or 3-word phrases by 2 yr. The average 3-yr-old child can carry on a conversation. A 4-yr-old child can tell simple stories and can engage in conversation with adults or other children. A 5-yr-old child may have a vocabulary of several thousand words.


Cognitive Development

Cognitive development refers to the intellectual maturation of children. Increasingly, appropriate attachments and nurturing in infancy and early childhood are recognized as critical factors in cognitive growth and emotional health. For example, reading to children from an early age, providing intellectually stimulating experiences, and providing warm and nurturing relationships all have a major impact on growth in these domains.

Intellect is appraised in young children by observations of language skills, curiosity, and problem-solving abilities. As children become more verbal, intellectual functioning becomes easier to assess using a number of specialized clinical tools. Once children start school, they undergo constant monitoring as part of the academic process.

At age 2 yr, most children understand the concept of time in broad terms. Many 2- and 3-yr-old children believe that anything that happened in the past happened "yesterday," and anything that will happen in the future will happen "tomorrow." A child at this age has a vivid imagination but has difficulty distinguishing fantasy from reality.



Emotional and Behavioral Development


Emotional growth and the acquisition of social skills are assessed by watching children interact with others in everyday situations. When children acquire speech, the understanding of their emotional state becomes much more accurate. As with intellect, emotional functioning can be delineated more precisely with specialized tools.

Crying is infants' primary means of communication. Infants cry because they are hungry, uncomfortable, distressed, and for many other reasons that may not be obvious. Infants cry most—typically 3 h/day—at age 6 wk, usually decreasing to 1 h/day by age 3 mo. Parents typically offer crying infants food, change their diaper, and look for a source of pain or discomfort. If these measures do not work, holding or walking with the infant sometimes helps. Occasionally nothing works. Parents should not force food on crying infants, who will readily eat if hunger is the cause of their distress.

At about age 8 mo, infants normally become more anxious about being separated from their parents. Separations at bedtime and at places like child care centers may be difficult and can be marked by temper tantrums. This behavior can last for many months. For many older children, a special blanket or stuffed animal serves at this time as a transitional object that acts as a symbol for the absent parent.


At age 18 mo to 2 yr, children typically begin to establish gender identity. During the preschool years, children also acquire a notion of gender role, of what boys and girls typically do. Exploration of the genitals is expected at this age and signals that children are beginning to make a connection between gender and body image.




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* This is the Professional Version. *