Breast Changes

The earliest outward changes of puberty occur in the breasts. First, the nipple enlarges and protrudes. The areola surrounding the nipple enlarges and becomes somewhat protuberant, although less so than the nipple. These changes are followed by growth of the glandular and ductal tissue. Fat is deposited in the breasts. During puberty, a girl’s breasts may develop at different rates, resulting in a temporary lopsided appearance.

Body Contours

The pelvis widens and assumes a rounded, basin-like shape that is favorable for passage of the fetus during childbirth. Fat is deposited selectively in the hips, giving them a rounder appearance than those of the male.

Body Hair

Pubic hair appears downy at first but becomes thicker as puberty progresses. Axillary hair appears near the time of menarche (menstrual onset). The texture and quantity of pubic and axillary hair vary among women and in different ethnic groups. Women of African descent usually have body hair that is coarser and curlier than that of white women. Asian women often have sparser body hair than women of other racial groups.

Skeletal Growth

In response to estrogen stimulation, girls grow taller for several years during early puberty. The growth spurt begins about 1 year after initial breast development. Estrogen’s other powerful effect on the skeleton is to cause the epiphyses (growth areas of the bone) to unite with the shaft of the bones; this development eventually stops height growth.

Reproductive Organs

The girl’s external genitalia enlarge as fat is deposited in the mons pubis, labia majora, and labia minora. The vagina, uterus, fallopian tubes, and ovaries grow larger. Vaginal mucosa changes, becoming more resistant to trauma and infection in preparation for sexual activity. Changes in the reproductive organs occur during each female reproductive cycle.

Menarche

Early menstrual periods are often irregular and scant. Early menstrual cycles are not usually fertile because ovulation occurs inconsistently. Fertile reproductive cycles require preparation of the uterine lining precisely timed with ovulation. Ovulation may occur during any female reproductive cycle, however, including the first. The sexually active girl can conceive even before her first menstrual period.

Delayed onset of menstruation is called primary amenorrhea if the girl’s periods have not begun by the age of 16 years. Amenorrhea, or absence of menstruation, also may be considered primary if the girl is more than 1 year older than her mother or sisters were when their menarche occurred. Secondary amenorrhea describes absence of menstruation for at least three cycles after regular cycles have been established. Both primary and secondary amenorrhea are more common in females who are thin because they may have too little fat to produce enough sex hormones to stimulate ovulation and menstruation. Pregnancy is a common cause of secondary amenorrhea as well.

Nocturnal Emissions

Often called “wet dreams,” nocturnal emissions are common during adolescence. The boy experiences a spontaneous ejaculation of seminal fluid during sleep, often accompanied by dreams with sexual content. Boys should be prepared for this normal occurrence so that they do not feel abnormal or ashamed.

Body Hair

Pubic hair growth begins at the base of the penis. Gradually the hair coarsens and spreads upward and in the midline of the abdomen. About 2 years later, axillary hair appears. Facial hair begins as a fine, downy mustache and progresses to the characteristic beard of the adult male. In most boys, chest hair develops, and some have hair on their upper backs. The amount and character of body hair vary among men of different racial groups, with Asian and Native American men often having less than white or Black or African-American men.

Body Composition

Testosterone causes a male to develop a greater muscle mass than a female. At maturity, a man’s muscle mass exceeds a woman’s by 50%.

Skeletal Growth

Testosterone causes boys to undergo a rapid growth spurt, especially in height. A boy’s linear growth begins about a year later than a girl’s and lasts for a longer time, resulting in the male’s greater average height at maturity. Testosterone causes union of the epiphysis with the shaft of long bones, as does estrogen. The height-limiting effect of testosterone in the male is not as strong as that of estrogen in the female, so boys grow in stature for several years more than girls.

A boy’s shoulders broaden as his height increases. His pelvis assumes an upright shape, with a narrower diameter and heavier structure than the female’s.

Voice Changes

Hypertrophy of the laryngeal mucosa and enlargement of the larynx cause the male’s voice to deepen. Before reaching the lower-pitched voice at maturity, many boys experience “cracking” or “squeaking” of their voices when they speak.