Final answer:
Growth during infancy and childhood is not steady, with a slowdown between 4 and 6 years old. Females experience a pubertal growth spurt after 8-9 years old. Growth in weight shows a similar spurt during adolescence.
Step-by-step explanation:
Growth during infancy and childhood is not steady, with a slowdown between 4 and 6 years old. During this time, children gain 5-7 pounds and grow about 2-3 inches per year. After reaching 8-9 years old, females experience a pubertal growth spurt, which continues until around 12 years old.
Growth in weight shows a similar spurt during adolescence, partly due to growth in height, muscle, bone, and body fat. Boys' growth in weight lags behind their growth in height by about three months, while girls' lag time is about six months.
The growth rates are represented in graphs showing the 50th percentile for height increase, which reveals a sharp growth spurt during adolescence, although not as rapid as during infancy.