Physical growth and development in Infancy

We will see rapid changes in an infant’s body and brain support learning, motor skills, and perceptual capacities. One reason for the vast changes in what children can do over the first two years is that their bodies change enormously—faster than at any other time after birth. So, here, we are going to trace physical growth and development in infancy.

One of the most obvious changes in infants’ appearance is their transformation into round, plump babies by the middle of the first year, showing the physical growth and development in infancy. This baby fat gain helps infants to maintain body temperature. As the child’s size increases, different parts of the body grow at different rates.

Changes in body proportion.

There are two growth patterns, the first is cephalocaudal trend (Latin for “head to tail”). During the prenatal period, the head develops rapidly as compared to other parts of the body. At birth, head takes up one-fourth of total body length.

The second  pattern is proximodistal trend. In this pattern, growth proceed from near to far- from center of the body outward. In the prenatal period, the head, chest, and trunk grow first; then the arms and legs; and finally the hands and feet. During infancy and childhood, the arms and legs continue to grow somewhat ahead of the hands and feet.

Children of the same age differ in rate of physical growth; some make faster progress toward a mature body size than others. But current body size is not enough to tell us how quickly a child’s physical growth is moving along.

Brain development.

The human brain has 100 to 200 billion neurons, or nerve cells, that store and transmit information. Between them are tiny gaps, or synapses, where fibers from different neurons come close together but do not touch. Neurons send messages to one another by releasing chemicals called neurotransmitters. The basic story of brain growth concerns how neurons develop and form this communication system.

A surprising aspect of brain growth is programmed cell death, which makes space for these connective structures. Brain development can be compared to molding a “living sculpture.” First, neurons and synapses are overproduced. Then, cell death and synaptic pruning sculpt away excess building material to form the mature brain—a process jointly influenced by genetically programmed events and the child’s experiences.

Researchers distinguish between two types of brain development. First, experience-expectant brain growth. It refers to the young brain’s rapidly developing organization, which depends on ordinary experiences to explore the environment, hear language and interact with people.

The second is experience-dependent brain growth. It consists of additional growth and refinement of established brain structures as a result of specific learning experiences.

Motor development.

Gross-motor development refers to control over actions that help infants get around in the environment, such as crawling, standing, and walking.

Fine-motor development has to do with smaller movements, such as reaching and grasping.

It also presents the age range during which most babies accomplish each skill, indicating large
individual differences in rate of motor progress. Children acquire motor skills in highly individual ways. Babies display such skills as rolling, sitting, crawling, and walking in diverse orders rather than in the sequence implied by motor norms (Adolph & Robinson, 2013).

To learn in detail about the motor development in infants, click here.



  1. Robert. S. Feldman. (2017). Development Across the Lifespan. (8th ed.). Pearson Education.
  2. Laura. E. Berk. (2018). Development Through the Lifespan (7th ed.). Pearson Education.

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