For preteens who are eager for adulthood, the arrival of puberty may seem to take forever. In relation to other milestones of puberty, such as breast growth for girls and a deepening voice for boys, the growth of underarm hair fits into a predictable timetable of events, as part of the body's natural response to the influx of adult hormones.
Significance
The growth of armpit hair is triggered by the release of sex hormones, and the maturation of pheromone-producing glands in the armpit. From a scientific standpoint, pheromones cause a positive sexual response in mammals and are considered important for reproductive purposes. This can begin as early as 11 years old in less than 3 percent of teens.
Time Frame
Underarm hair can begin to grow as late as age 17, with 96 percent of teens seeing their first growth by the time they're 15, and 95 percent reporting full growth by the time they're 19. Growth occurs slowly, with an average of 3 to 4 years from the time that hair begins to grow until a complete region of growth is reported.
Identification
For boys, approximately 2 years after pubic hair begins to develop, armpit hair grows in the crease between the arm and the torso, and can be seen when the arms are raised above the head. The hair under the arms begins to grow slowly, with just a few thin, wispy strands appearing at first. They may have little or no color, but as time goes by, more hair of darker color will appear in the area. In both boys and girls, acne begins to develop around the same time.
Benefits
Armpit hair wicks moisture away from the skin, which can harbor odor-causing bacteria. In many European cultures, women do not shave their underarms. In fact, in many places, armpit hair is considered sexy. For girls, armpit hair begins to grow around the same time pubic hair begins to grow.
Misconceptions
Some people believe that shaving armpit hair causes it to be darker and thicker. In reality, the flat ends of hair that has been shaved tend to look thicker and darker than the slender tapered ends of hair that has been left to grow naturally.
Potential
The amount of armpit hair you will develop is predetermined by genetics. If your parents tend to have thick, dark patches of underarm hair, chances are that you may develop it too. Likewise, if your parents tend to have thinner, lighter hair, with less pronounced growth, that will be your legacy.
Considerations
An absence of armpit hair and other signs of puberty by age 15 could be cause for concern. Doctors can check hormone levels and recommend hormone therapy, if necessary. Everyone develops on his own schedule, which is mostly based on heredity, and may begin as late as 16 or 17 years old.
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