Mark N. Skelton, MA, EMDR
Basic Trained EMDR Clinician | Cognitive Skills Trainer
Doctoral Student, Clinical Psychology (KCU)

Childhood development is analogous to building a LEGO castle. It is a step-by-step procedure that requires time, different phases and the accumulation of parts. In the same sense, childhood development is a cumulative process built upon critical periods, multiple stages and the overlap of various dimensions. The following three-part blog series will describe childhood development through the multiple layers of biology, cognition and interpersonal relationships. More specifically, they will detail prenatal and postnatal brain growth along with the major theories of cognitive and socio-emotional development. The series will itemize these three developmental categories through the lens of scientific literature and developmental theorists starting with the biological development of the brain.

First & Second Trimester

Without a brain the human experience would essentially be non-existent. Accordingly, it makes sense to examine the neurobiological development of a child’s before their cognitive and social construction. The human brain is a “work in progress” that continually reinvents itself even after childhood. Nevertheless, the major stages of brain growth are the prenatal and postnatal periods. Starting in gestation, the individual brain begins to develop from the inside out, or from the brain stem to the prefrontal cortex (Field et al., 2017). During the first trimester, the “primitive” areas of the nervous system, including the brain and spinal cord, take form. Neurogenesis, growth and development of brain cells, begins after about 50 days in utero (Field et al., 2017). At its height of production, neurons can produce at an astonishing rate of 250,000 new neurons per minute! This process begins to slow in the second trimester and the cerebral cortex becomes the largest structure of the prenatal brain (Field et al., 2017). By this time, the brainstem and midbrain system are controlling the essential body functions of respiration, breathing, appetite and sleep cycles (Davies & Troy, 2020).

Third Trimester

During the third trimester, the brain synapses begin to form between the neurons at a rate of 40,000 per minute (Bourgeois, 1997). This process contributes to the tripling in brain volume during the last prenatal period (Field et al., 2017). The myelination process starts around the seventh month. This operation allows faster transmission of neural impulses as fatty myelin cells form around dendritic axons insulating them as plastic coating on electric wires (Davies & Troy, 2020). By this time, the brain stem, limbic system and neocortex are myelinated and allow the functions of basic survival functions, rational thinking, planning, decision making and emotional regulations. It is important to note that the third trimester is a critical period in which the brain is most vulnerable to injury by both internal and external factors (Field et al., 2017).

Post-natal Development

Brain development is a lengthy and gradual process that continues even after infant birth. Neural growth and myelination continues until roughly the third year of life (Jernigan et al, 2011). This continued growth allows brain volume to reach nearly 90% of an adult size by the age of 6 years old (Stiles & Jernigan, 2010). This overproduction of neuron and synaptic growth primes a child for rapid learning.  Synapses that are not used are “pruned away” throughout childhood and adolescence in a process known as “Synaptic Pruning” (Huttenlocher & Dabholkar, 1997).

These beginning years of growth are most critical to development and set the tone for development in later life (Knickmeyer et el., 2008). Young children advance from crawling to walking as well as progress from using primarily motor reflexes to using their senses and vocalization. Language significantly influences communication and is characterized by symbolic systems. These factors play a vital role in different forms of attachment, interpersonal relationships and social cognitive skills (Field et al., 2017).


As demonstrated, brain development begins in the womb. Brain development is a sophisticated and complex process that continues after birth and even into adulthood. It is important to know that brain development is influenced by environment factors such as screen time, parenting, social relationships and lifestyle. This information is for the public square and personal enrichment of the reader. The following blogs will examine cognitive and psychological development in infants, toddlers and preschoolers.



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Davies, D. & Troy, M. (2020). Chlild development: A practitioner’s guide (4th ed.).The Guildford Press.

Field, T.A., Jones, L.K., & Russell-Chapin, L.A. (2017). Neurocounseling: Brain-based clinical approaches.
American Counseling Association.

Huttenlocher, P.R., & Dabholkar, A. S. (1997). Regional difference in synaptogenesis in the human
cerebral cortex. Journal of Comparative Neurology, 387, 167-178.

Knickmeyer, R. C., Gouttard, S., Kang, C., Evans, D., Wilber, K., Smith, J. K., & Gilmore, J. H. (2008). A
structural MRI study of human brain development from birth to 2 years. Journal of
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Stiles, J., & Jernigan, T.L. (2010). The basics of brain development. Neuropsychology Review, 20, 327-

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