Adolescence is the transition period between childhood and adulthood, characterized by impulses of physical, mental, emotional, sexual and social development and by the individual’s efforts to achieve goals related to the cultural expectations of the society in which he or she lives. Adolescence begins with the bodily changes of puberty and ends when the individual consolidates his or her growth and personality, progressively achieving economic independence, in addition to integration into his or her social group(2).

The chronological limits of adolescence are defined by the World Health Organization (WHO) as between 10 and 19 years of age ( adolescents ) and by the United Nations (UN) as between 15 and 24 years of age ( youth ), a criterion used mainly for statistical and political purposes. The term young adults is also used to encompass the age group from 20 to 24 years of age ( young adults ). Currently, it is more convenient to group both criteria together and call them adolescence and youth or adolescents and youth in community programs, thus encompassing university students and also young people who join the armed forces or participate in social support projects called youth protagonism . In the health standards and policies of the Brazilian Ministry of Health, the limits of the age range of interest are the ages of 10 to 24.

In most countries, the concept of legal majority is established at 18 years of age, but other criteria exist and remain flexible and confusing, according to local customs and cultures.

In Brazil, the Child and Adolescent Statute (ECA), Law 8,069 of 1990, considers a child to be a person under 12 years of age and defines adolescence as the age range from 12 to 18 years of age (article 2 ) , and, in exceptional cases and when provided for by law, the statute is applicable up to 21 years of age (articles 121 and 142). Adolescents may have the optional vote as voters and citizens from the age of 16. The concept of minor is implied for those under 18 years of age.

It is important to emphasize that, due to the characteristics of variability and diversity of biological and psychosocial parameters that occur at this time, and called maturation asynchrony , chronological age, despite being the most commonly used criterion, is often not the best descriptive criterion in clinical, anthropological, and community or population studies(4).

Pubertyis the biological phenomenon that refers to the morphological and physiological changes (shape, size and function) resulting from the reactivation of the neurohormonal mechanisms of the hypothalamic-pituitary-adrenal-gonadal axis. These bodily changes known as the phenomena of pubarche or adrenarche and gonadarche are part of a continuous and dynamic process that begins during fetal life and ends with the complete growth and total fusion of the bone epiphyses, with the development of secondary sexual characteristics, with the complete maturation of women and men and their capacity for fertilization, through ovulation and spermatogenesis, respectively, ensuring the perpetuation of the human species(2).

It is important to note that there is enormous variability in the time of onset, duration and progression of pubertal development, with marked differences between the sexes and between the different ethnic and social groups of a population, including according to nutritional status and family, environmental and contextual factors. Menarche characterizes the first menstruation of the adolescent, commonly known by the term “young lady” , and occurs on average at 12.8 years of age, with a significant difference of 12.18 years for urban areas and 12.89 years for rural areas of the country(5). In Brazil, the Brazilian Society of Pediatrics (SBP) and the Federal Council of Medicine (CFM) consider adolescence an area of ​​specialization within pediatrics, including in relation to undergraduate training, medical residency and hospital accommodation. The Ministry of Health, through its Technical Area for Adolescent and Youth Health (ASAJ), will soon be implementing the adolescent card throughout the country , covering the age group from 10 to 19 years, 11 months and 29 days, including a final message addressed to the young adult, and which will include various data on growth and development for monitoring, including immunization and prevention of communicable diseases, aiming at a better future for a population estimated at 35.3 million Brazilians residing in the country. REFERENCES 1. WHO, World Health Organization. Young People´s Health – a Challenge for Society. Report of a WHO Study Group on Young People and Health for All. Technical Report Series 731. Geneva: WHO, 1986. 2. Tanner JM. Growth at Adolescence. 2nd ed. Oxford: Blackwell, 1962. 3. BRAZIL. Law 8,069 of July 13, 1990. Statute of the Child and Adolescent. Brasília: Ministry of Justice, 1990. 4. Eisenstein E. Pubertal delay and chronic malnutrition. 1999. Doctoral Thesis – Paulista School of Medicine, Federal University of São Paulo (UNIFESP).

5. Brazil/INAN/PNSN. National Survey on Health and Nutrition. Growth Profile of the Brazilian Population from 0 to 25 years. Brasília: INAN/MS. 1992.

6. SBP, Brazilian Society of Pediatrics. Adolescent care. In: Adolescence Guide – Scientific Department of Adolescence of the SBP. Rio de Janeiro: SBP, 2000.

7. Brazil/MS. Adolescent Card (preliminary document). Technical Area of ​​Adolescent and Youth Health. ASAJ/MS, Brasília: MS, 2004.

8. Brazil/IBGE. Children and adolescents, social indicators. Brasília: IBGE, 2004.

1. Professor-PhD at the School of Medical Sciences of the State University of Rio de Janeiro (FCM/UERJ), Center for Studies on Adolescent Health (NESA), Center for Integrated Studies of Childhood, Adolescence and Health (CEIIAS)