Child Development Concepts

Child development is a continuous process of acquiring new and advanced skills. This development depends on maturation of the nervous system. Although typical child development follows a relatively consistent sequence, it is not linear. Instead, there are spurts and lags. For example, motor development in the first year of life proceeds relatively rapidly. Babies typically mature from being completely immobile to walking in just over 12 months, but then motor development progresses less dramatically during the second year of life. Conversely, language development in the first year of life occurs slowly, but there is an explosion of language acquisition between a child’s first and second birthdays.

On average, most children achieve each developmental milestone within a defined and narrow age range (Table 7.1). Usually physicians learn the average age for acquiring specific skills. However, since each developmental skill can be acquired within an age range, it is much more useful clinically to know when a child’s development falls outside this range. These so-called red flags are important because they can be used to identify when a child has developmental delay for specific skills. For example, although the average age of walking is approximately 13 months, a child may walk as late as 17 months and still be within the typical developmental range. In this example, the red flag for independent walking is 18 months, and a child who is not walking by 18 months of age is delayed.

Developmental History

Child development is classically divided into five interdependent domains or streams: gross motor, fine motor and problem-solving, receptive language, expressive language, and socialization/adaptive. The approach to a child with possible developmental delays is based on a working knowledge of these domains and the typical age ranges for acquiring specific milestones within each domain. Therefore, the clinician should begin the evaluation of a child with developmental concerns by obtaining a developmental history, and emphasis should be placed on the pattern of milestone acquisition as well as the child’s current developmental skills. Clinicians working in a busy clinical setting may need to base this history primarily on the caregiver’s report of the child’s developmental abilities. Clinicians may also use standardized tools to aid in this portion of the history, including the Ireton Child Development Inventory (CDI), the Ages and Stages Questionnaire (ASQ), and the Parents’ Evaluation of Developmental Status (PEDS). However, if the clinician’s history confirms a developmental disability, standardized testing by a developmental specialist or clinical psychologist should be strongly considered; this formal evaluation will provide a much better assessment of the child’s developmental abilities.

When there is concern about developmental delay in a child, a developmental quotient should be calculated. The developmental quotient is the ratio of the child’s developmental age over the chronological age. The developmental quotient should be calculated for each developmental stream. Typical development is a developmental quotient greater than 70%, and atypical development it is a developmental quotient less than 70%. Toddlers and young children with atypical development are at risk for lifelong developmental problems. The term global development delay is used if a child younger than 5 to 6 years of age has a developmental quotient less than 70% in two or more domains. Children with global developmental delay should receive a thorough medical evaluation to try to determine the cause of the delay and begin management for their developmental disabilities.

Neurological and Other Medical History

For children with global developmental delay, the clinician should obtain a thorough medical history, including a detailed neurological history. Pertinent aspects of the history include the presence of any other neurological condition such as epilepsy, vision or hearing impairments, ataxia or a movement disorder, sleep impairment, and behavioral problems. The clinician should also inquire about prenatal, perinatal, and postnatal factors that can impact a child’s development (Tables 7.2 and 7.3). The social history should probe for environmental factors that can affect development, including physical or other forms of abuse, neglect, psychosocial deprivation, family illness, impaired personalities in family members, sociocultural stressors, and the economic status of the family.

Table 7.2 Etiology of Developmental Delay by Time of Onset

CNS, Central nervous system.

From Sherr, E.H., Shevell, M.I., 2006. Mental retardation and global developmental delay, in: Swaiman, K.F., Ashwal, S., Ferriero, D.I. (Eds.), Pediatric Neurology, Principles and Practice, fifth ed. Mosby, Philadelphia.

Table 7.3 Perinatal Risk Factors for Neurologic Injury

From Sherr, E.H., Shevell, M.I., 2006. Mental retardation and global developmental delay, in: Swaiman, K.F., Ashwal, S., Ferriero, D.I. (Eds.), Pediatric Neurology, Principles and Practice, fifth ed. Mosby, Philadelphia.

Though families now typically have fewer children, and the caregivers’ knowledge of family history is frequently quite limited, the clinician should still make an effort to obtain a three-generation pedigree. The pertinent aspects of the family history include developmental disabilities, special education services or failure to graduate from school, neurodegenerative disorders, multiple miscarriages or early postnatal death, ethnicity, and consanguinity. If a specific genetic syndrome is suspected, the clinician should inquire about the presence in other family members of medical problems associated with that syndrome. For example, if the child has the features of fragile X syndrome, the family history should include questions about maternal premature ovarian failure, parkinsonism or ataxia of unknown etiology in the maternal grandfather, and intellectual disability or learning problems in an X-linked pattern.

Physical Examination