During early childhood – from about ages 1 to 4 years – healthy children continue growing and developing in all areas, physically, mentally and emotionally.

During infancy, babies gain weight, grow and begin all areas of development. From ages 1 to 4, this development progresses at different rates in each area. Physically, most children attain a height that is double their length at birth by the time they are 4 years old. They also gain muscle control, balance and eye-hand coordination, which enable them to master basic motor skills, such as being able to walk more steadily, run, and kick and throw a ball.

In addition to increased musculoskeletal strength, children experience huge developmental changes in their cognitive and language abilities during these formative years. By their fourth birthday, most children speak in sentences of four to six words, have a vocabulary of more than 1,500 words and understand the concept of counting.

Healthy children grow and develop at their own pace. Some children may achieve various developmental milestones earlier or later than others and still be within the normal range. Children who were born prematurely may lag slightly. Generally, by age 2, developmental differences between a premature child and a full-term one are minimal.

Parents can observe children as they reach particular milestones. Although mild delays are not a cause of concern, failure to reach a milestone may signify some type of developmental delay. In early childhood, these may include failure to thrive, not being able to throw a ball overhand or ride a tricycle, showing no interest in interactive games, not using the personal pronouns “me” and “you” appropriately or not responding to people outside the family.

Possible causes of developmental delays during early childhood include premature birth, lack of adequate nutrition, congenital conditions (e.g., fetal alcohol syndrome), autism or mental retardation. In addition to developmental delays, some children may lose skills that they already mastered, such as communicating with others. These may be related to conditions around them (e.g., birth of a sibling) or may also be signs of serious conditions such as pervasive developmental disorders.

All the stages of early childhood development can be monitored when children receive regular checkups with a pediatrician. During early childhood, the American Academy of Pediatrics (AAP) recommends well-child visits at age 12 months, 15 months, 18 months, 2 years, 3 years and 4 years.