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Toddler Development

Michael A. Davis, MD

Toddlerhood consists of the years from about 1 to 3 years of age. Dramatic advances occur in language, interpersonal skills, and affective, motor, cognitive and physical growth. Affective development is highlighted by the toddler's striving for autonomy and independence, attachment to family, and the development of impulse control. Cognitive development is characterized by the transition from sensorimotor to preoperational thought.

Growth Rate and Physical Appearance

After the rapid growth of infancy, the rate of growth slows in the toddler years. After age 2, toddlers gain about 5 lb in weight and 2.5 inches in height each year. Head circumference only increases by about 1 inch from 2 to 12 years. Growth often occurs in spurts. Between the ages of 2 and 2.5 years, the child will have reached 50% of his adult height.

Growth of the lower extremities often is accompanied by tibial torsion and physiologic bowing of the legs, which usually corrects by age 3 years. The percentage of body fat steadily decreases from 22% at age 1 year to about 15% at age 5 years.

Gross Motor Skills

Complex gross motor patterns rapidly develop, and balance and coordination improve. Most children walk without assistance by 18 months.

At 2 years, the stiff, wide-leg gait of early toddlerhood becomes a flexible, steady walking pattern, with heel-toe progression.

Fine Motor Skills

Fine motor development during toddlerhood consists of refinements in reaching, grasping, and manipulating small objects.

The 18-month-old can make a tower of four blocks. One year later, he can stack eight blocks. Most 18-month-olds will hold the crayon in a fist and scribble spontaneously on paper.

Affective Development

Autonomy and Independence

Because of improved motor skills, the transition from infancy to toddlerhood is marked increased autonomy and independence. The child can move easily away from the parent and begins to test boundaries and limits.

The toddler may refuse to eat unless allowed to feed himself, and the child may no longer may be willing to try new foods.

Impulse Control. Toddlers begin to develop impulse control. The 18-month-old may have minimal impulse control and display several temper tantrums each day. Most 3-year-olds have some degree of self-control.

Successful toileting usually occurs toward the end of the third year when the child becomes able to control his sphincter, undress, get onto the potty, and has the willingness to participate. Although toilet training may be introduced at an earlier age, success with consistent daytime dryness usually is not achieved until about 2.5 years of age.

Attachment

Attachment refers to the bond that forms between the infant and the caregiver.

Disorders of attachment may result from inconsistent caregiving and are more common in the presence of poverty, drug use, or emotional illness. Affected toddlers may not show interest in exploring the environment.

Temperament determines how a child approaches a given situation. Ten percent of children are less adaptable and tend to be emotionally negative and are considered "difficult". About 40% of children are "easy," having regular eating and sleeping schedules, adapting well to new situations, and having positive moods. About 15% of toddlers are "slow-to-warm-up," and they are quiet and take longer to adapt to new situations.

Cognitive Development

Toddlerhood is characterized by a transition from sensorimotor to preoperational thinking. During the sensorimotor period, the infant primarily learns about the world by touching, looking, and listening. Preoperational thought is marked by the development of symbolic thinking, as the child becomes capable of forming mental images and begins to solve problems by mental trial and error. Progression from sensorimotor to symbolic thought occurs typically between 18 and 24 months of age. The child understands that one object can represent another during play (eg, a block can serve as a car).

Complete object permanence has developed, and the child can find an object under a blanket, despite not seeing it hidden.

By 3 years, he can draw primitive figures that represent important people in his environment, and he develops elaborate play and imagination.

Language

Beginning around age 2 years, toddlers use language to convey their thoughts and needs (eg, hunger). The 18-month-old has a vocabulary of at least 20 words, consisting primarily of the names of caregivers, favorite foods, and activities, he may be starting to put two words together.

After 18 months the toddler begins to put together phrases. Early two and three word sentences are referred to as "telegraphic speech," and about 50% of what the child says should be intelligible to strangers.

By the age of 3 years, the vocabulary increases to about 500 words, and 75% of speech is understandable to strangers. He begins to make complete sentences, and frequently asks "why" questions.

Language development is influenced by environmental factors and innate abilities. Parents should be encouraged to provide an environment that will foster language growth by talking and reading aloud to the child every day.

Developmental Monitoring and Anticipatory Guidance

When developmental surveillance suggests delay, a screening test is necessary. When the screening test confirms delay, the clinician should refer the child for a more extensive developmental assessment.

Anticipatory Guidance

During the 12-month visit, the pediatrician should explain that the child soon will begin to experience struggles over autonomy and independence.

More frequent temper tantrums can be expected in the second year of life as the toddler encounters frustration while seeking autonomy. §