Physical Development in Adolescence

As children transition into adulthood, their bodies go through a series of changes during a process known as puberty. These changes are important and necessary, as they ultimately make children capable of reproduction. However necessary the process are, going through puberty is often a confusing time for the child, as some of these changes seem to occur overnight. Make yourself readily available to offer reassurance and guidance when needed.

Teens enter puberty at different ages, depending on lifestyle and genetics. Credit: BananaStock/BananaStock/Getty Images


Many physical developments during adolescence are initiated by hormone signals that start in the brain and go to children's respective gonads. In boys, hormone signals tell the testes to begin producing sperm as well as testosterone, which is responsible for most of the changes in a boy's body in puberty. In girls, the hormones signal the ovaries to start producing estrogen, which prepares girls to start having menstrual periods. Areas of the body affected by the influx of hormones are the brain, muscles, bones, skin, breasts and reproductive organs.

First Signs

According to the Lucile Packard Children's Hospital at Stanford, girls generally begin puberty before boys. In girls, the average age at onset is between 8 and 13 years, whereas in boys it's between 9.5 and 14 years. The first sign of puberty's onset in girls is breast development, soon followed by pubic hair development. Boys will generally experience enlargement of the testicles, followed by penis enlargement about one year later.

Changes in Boys

In addition to a boy's testicles and penis growing larger during puberty his body becomes broader and more muscular during puberty. Some boys experience a brief period of breast growth that eventually subsides by the end of puberty. A male's voice also becomes deeper, sometimes "cracking" along the way between higher and lower tones before it settles on a pitch. Moreover, boys' gain thicker body hair and begin to develop pubic hair, as well as hair under the arms and on the face.

Changes in Girls

Girls' bodies become more curvaceous as their breasts develop, their hips broaden, and they gain more body fat. Sometimes a girl's breasts grow at different rates, but eventually they settle on a similar size. The areolas, or the dark areas of skin surrounding the nipples, also increase and form projections on the breasts, but eventually only the nipples will be erect. In addition to developing pubic hair, girls also begin to develop hair under their arms. The major signal that a girl is able to reproduce is that she starts to have a menstrual period, which generally begins sometime between 10 and 16.5 years of age.

Body Growth

Children gain a lot of height during their teen years. According to the Virginia Tech Cooperative Extension online, girls generally grow an average of 3.5 inches and boys grow about 4.1 inches during puberty. Girls typically grow between one and two more inches after menstruation, ultimately reaching their adult height by about 14 or 15 years depending upon when they started to go through puberty. Boys, on the other hand, usually gain more height two years later than girls, according to KidsHealth online. Most boys have stop growing by age 16, but their muscles continue to develop.

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