Normal child development is the essence of childhood that leads to transition of a fertilized ovum into an independent adult through different stages of anatomical growth and physiological maturation. The terms growth and development are not interchangeable, though both processes are frequently interdependent.
It is “an anatomical process involving increase in the physical size of an organ, tissue and body, by multiplication or enlargement of cells”. It can be easily measured in terms of increase in anthropometric parameters.
Normal child development denotes “physiological or functional maturation of various organs or systems, acquisition of newer functions or skills and adaptation to the environment.” Unlike growth, precise measurement of development is difficult, though the achievement of various neurological milestones may be used as general indicator of development.
Normal child development
Although the development is multi-dimensional process, this term is popularly used in connection to neurological and psychosocial maturation.
Factors, which affect growth, may also affect development. However, two most important factors for Normal child development are normal brain growth and adequate emotional stimulation.
Most critical period for brain growth extends from mid- gestation till 2 years of age, characterized by explosive growth in neuronal cells, neurological proliferation and progressive myelination. Nearly 90% of brain growth is complete by two years of age. Hence, any CNS insult during early childhood e.g. hypoxia, infections or trauma, often leaves severe and irreversible neurological sequelae.
GENERAL PRINCIPLES OF Normal child development
Like growth, Normal child development also follows the laws. It is also a continuous and orderly process that occurs in cephalocaudal direction. In addition, it is important to note that —
a) Normal child development is a qualitative parameter, which is difficult to measure precisely. A baby may be able to perform a single milestone e.g. sitting, with variable degrees of maturity at different ages. Hence, it is difficult to pinpoint the age at which a particular milestone was achieved. Developmental assessment consists not so much of observing what a child does, but how he does it.
b) Individual pace of Normal child development is variable. Some children are rapid developers, while others are slow developers. Hence it is important to exercise utmost caution, before declaring a child as developmentally delayed.
c) Pace of Normal child development may differ in different fields. Four major fields of development include — a) Gross motor, b) Fine motor, c) Psychosocial and d) Language. Some children develop slowly in certain fields and faster in other fields. Global developmental delay i.e. delay in all major fields is almost always due to neurological causes, while isolated or selective developmental delay in one or two fields may be due to CNS or non-CNS causes e.g. poor muscle mass due to malnutrition (gross motor delay), abnormal hearing (linguistic delay) or vision (psychosocial delay).
d) General sequence of achieving developmental milestones is fairly consistent, despite individual variations in the pace of development. Thus, it is extremely rare to achieve a later milestone e.g. sitting, until the earlier milestone e.g. neck holding, has been achieved.
e) Disappearance of primitive reflexes is also a part of development – Certain primitive neonatal reflexes e.g. grasp or stepping reflex, have to disappear before the corresponding voluntary function e.g. voluntary grasp or standing is achieved. Persistence of a neonatal reflex beyond the expected age of its disappearance, by itself indicates Normal child development problem, as seen in cerebral palsy.