The period occuring after birth.
Infancy: refers to the earliest peroid of extrauterine life, roughly the first year after birth.
An infant aged 1 month or younger is called a Newborn or Neonate
Characteristics: Transition from intrauterine to extrauterine existence requires many critical changes, especially in the cardiovascular and respiratory system.If newborn infants survive the first crucial hours after birth,their chances of living are usually good.The body as whole grows particularly rapidly during infancy; total length increases by approximately one half and weight is usually tripled. By 1 year of age,most children have six to eight teeth.
Childhood : is the peroid from aprproximately 13 months until puberty (13months - 11 year)
Characteristics :The primary ( deciduous ) teeth continue to appear and are later replaced by the secondary ( permanent ) teeth. During early Childhood, there is active ossification (formation of bone ), but as the child becomes older, the rate of body growth slows down. Just before puberty, however, growth accelerates- the prepubertal growth spurt.
Puberty : Occurs usually between the ages of :-
Girls: 12-15 years
Boys: 13-16 years
Characteristics : During which secondary sexual characteristics develop and the capability of sexual reproduction is attained. The stages of pubertal development follow a consistent pattern and are defined by the appearance of secondary sexual characteristics (e.g., pubic hair development, Breasts in females, and growth of external genitalia in males). Puberty ends in females with the first menstrual period or menarche, the beginning of the menstrual cycles or periods. Puberty ends in males when sperms are produced.
Adolescence : is the period from approximately 11 - 19 years of age
Characteristics : Rapid Physical and Sexual maturation. It extends from the earliest signs of sexual maturity-puberty-until the attainment of adult physical, mental and emotional maturity. The ability to reproduce is achieved during adolescence. The general growth rate decelerates as this period terminates, but growth of some structures accelerates (e.g., female breasts and male genitalia).
Adulthood : attainment of full growth and maturity, is generally reached between the ages of 18 - 21 years.
Characteristics : Ossification and Growth are virtually completed during early adulthood (21-25 years). Thereafter, developmental changes occur very slowly.