Introduction

Understanding the pattern and time frame of normal development is an essential part of paediatric medicine. Whilst it is such an important building block in understanding children’s health, it may feel as though learning the sequence of early milestones is about as much fun as learning times tables at school. Like tables, however, a sound grasp of normal milestones is crucial when you are trying to make sense of child development.

Children follow a sequence of developmental skills. The age at which these skills are mastered can be compared within a large population of children, and normal ranges are described. This horizontal approach allows comparisons to be made with other children and is a good way of rapidly screening a population for those children who might be delayed.

For children who have delayed development it is important to compare the individual’s performance with their own previous performance (vertical assessment). This provides individual specific information about the rate of progress that will help to encourage and inform parents and professionals working with the child. Slowing in the rate of a child’s development is a worrying sign and may indicate a significant neurological disease.

In every developmental skill there may be differences in the quality of performance. Thus, most of us can kick a ball but, even with daily training, few of us could become a professional footballer. Certain skills are fundamental but as the tasks become more and more sophisticated, fewer individuals are able to acquire them.

Cross-sectional observation of many children at specific ages provides the basis of developmental tests such as the Denver Developmental Screening test, the Abilities of Babies and the Abilities of Young Children by Griffiths, the Bayley Scales of Infant Development and the Schedule of Growing Skills. Using these tests requires special training. All those working with children need to be able to perform an informal assessment of their development as outlined in this chapter.

Assessing an individual child’s development depends on:

The motor milestones

Play skills

Play skills develop rapidly in young children. Children who are uninterested in play should cause concern. The most common cause of loss of playfulness is that the child is unwell. However, a child who is said to be uninterested may be unable to play because of a physical difficulty or a learning difficulty. Another possibility is that the child has had limited play experiences and has been emotionally deprived.

Television is not an adequate substitute for playing with, and talking to, a baby.

Communication skills

The key milestones

There are three milestones, which, if not met, should ring ‘alarm bells’. These include:

Learning difficulty (mental retardation)

Learning difficulties are defined by IQ. A severe learning difficulty, as in the above case, is defined as an IQ of less than 35, moderate as an IQ of between 35 and 50, and mild as an IQ of between 50 and 70. The lower the IQ the more likely an organic explanation exists for the child’s difficulties. Increasingly, genetic causes of learning difficulties are being discovered. Inquire into alcohol use in pregnancy as fetal alcohol syndrome is a significant cause of mental retardation (see Chapter 18, page 266). A detailed family tree and questioning about the academic ability of relatives is useful; referral to a clinical geneticist may be of value, particularly if there are dysmorphic signs. Careful physical examination should seek any evidence of associated health problems and a careful search for dysmorphic features which might suggest a genetic problem. Investigation should be tailored to the individual case. See Table 4.1 for a list of tests, which should be considered.

Table 4.1 Investigations to be considered in a child with learning difficulties

Other common developmental disorders