American Medical Association Family Medical Guide - American Medical Association [221]
Most adolescents are preoccupied with their changing body and concerned about being and appearing normal. Boys may worry about their height and the size of their penis, and girls about their breasts and weight. The age at which body hair begins to grow and menstruation begins varies. Many boys and girls begin to develop earlier or later than the average ages. But if your child’s development is unusually early or late, see your pediatrician.
Physical and Sexual Development in Girls
Puberty can begin as early as age 8 or 9 in girls, with breast development as the first sign. It is not uncommon for one breast to begin to grow before the other. Breasts usually do not grow much beyond the age of 16. A girl should see her pediatrician if breast development has not begun by age 13.
Development of body hair varies greatly and depends largely on heredity. Pubic hair usually is noticeable at the start of puberty, while underarm hair begins to grow a year or two later (around age 12 or 13) and darkens and thickens as puberty progresses. An increase in perspiration under the arms and in the groin contributes to a body odor that does not occur in younger children.
Menstruation (see page 845) begins 2 to 3 years after the onset of puberty in girls at an average age of about 12 years. Menstruation often begins with extremely irregular menstrual periods (that are sometimes months apart) but periods usually become regular (about 3 to 7 days of menstrual flow every 28 days) about 2 to 3 years after a girl’s first period. Girls who have painful periods (see page 848) or who are extremely uncomfortable before their periods (premenstrual syndrome; see page 850) should see their doctor, who can recommend medication to prevent or lessen the discomfort associated with menstruation. Delayed periods (called primary amenorrhea) are usually the result of a naturally late onset of puberty, but it may be caused by a hormonal disorder or by an abnormality of the reproductive system.
A girl who is 14 years old and has not yet had a period, has not begun to develop breasts or pubic hair, and has not had a growth spurt should see her doctor. He or she will do a thorough evaluation that includes a health history, physical examination, and laboratory tests. If a girl has not started to menstruate by age 16 but is fully developed physically, she should see her doctor.
Precocious Puberty
Normal sexual development in children varies widely, mostly depending on heredity. Most girls start to go through puberty at about age 11 and boys at age 12 or 13. Precocious puberty is defined as the onset of sexual development before age 8 in girls and 9½ in boys. It occurs in about one out of every 5,000 children and is much more common in girls than in boys.
In most cases of precocious puberty (especially in girls), sexual development simply occurs earlier than expected, with no known cause. Some boys inherit a gene that brings on early puberty. About 15 percent of cases of precocious puberty result from underlying medical conditions such as central nervous system tumors (see page 682), Albright’s syndrome (a disorder characterized by a group of abnormalities including irregular skin-color patches, bone deformities, and early puberty), an underactive thyroid gland (hypothyroidism; see page 903), or adrenal gland disorders.
Some children who start puberty prematurely rapidly grow taller than their peers at first but end up being shorter because the hormonal changes stop their growth before they have reached a normal adult height. Children who develop early often feel different from their peers, which can sometimes cause emotional distress. A child who develops prematurely should be evaluated by his or her doctor.
To diagnose precocious puberty, doctors use blood tests to measure hormone levels, along with observation of a child’s physical changes and a complete physical examination. They may also order