Physical development between the ages of 11 and 14 years

Adolescence is a time of rapid growth in height and weight and of physical changes throughout the body. Most of these changes occur with puberty, which in the United States usually begins for girls between the ages of 9 and 11, and for most boys between the ages of 9½ and 13 years.

Breast buds-slight elevation and enlargement of the nipple area-are one of the first signs of puberty in girls. Pubic hair also usually starts developing around the same time. In boys, the first indication of puberty is that the testicles increase in size, followed by the growth of pubic hair and by penis lengthening.

Girls usually grow rapidly during early puberty and slow down with the first menstrual period, which typically begins around age 12, although the normal range is age 10 to 16½ years.¹ For boys, the height spurt occurs after other signs of puberty have developed. While boys lag behind girls in height in early adolescence, they generally end up being taller than girls, because once growth starts they grow at a faster rate and for a longer period of time. Girls reach their approximate adult height around 16 years of age, and boys at about 18 years of age.¹

Researchers have documented a long-term trend toward earlier puberty and larger growth related to better health and nutrition. Also, race seems to affect the timing of puberty. For example, girls who are black generally enter puberty earlier than girls who are white.

The surging hormones related to puberty often stimulate the sex drive in both males and females. It is normal for members of both sexes to masturbate in private. Hormones may also trigger episodes of difficult behavior, such as challenging parents and other authority figures.

Growth in body parts may occur out of sync with each other. For example, the nose, arms, and legs may grow faster than the rest of the body. Other physical development during puberty usually includes:

• Bone growth, accounting for nearly 25% of final adult height.
• An increase of about 15% in skull bone thickness; the forehead becomes more prominent and the jaw grows forward.
• Weight gain. The increase in weight during the growth spurt that happens with puberty typically accounts for about 40% of the final adult ideal body weight.¹
• Changes in body fat composition. Girls' body fat increases, while boys' decreases. Teens who are obese at the end of puberty are at increased risk for being obese during adulthood.²
• An increase in the size of organs. The heart doubles in weight, and lung size increases.
• Growth of facial hair in boys. Hair growth usually starts on the upper lip, gradually reaches the cheeks, and then the chin area.

Gynecomastia, the development of breast tissue, occurs in more than 60% of adolescent boys during early puberty to midpuberty. This resolves in 70% of boys within 1 year and 90% of boys in 2 years.³

Citations

1. Irwin CE, et al. (2003). The adolescent patient. In CD Rudolph, AM Rudolph, eds., Rudolph's Pediatrics, 21st ed., pp. 223–270. New York: McGraw-Hill.

2. Joffe A (2000). Why adolescent medicine? Medical Clinics of North America, 84(4): 769–785.

3. Ford CA, Coleman WL (1999). Adolescent development and behavior: Implications for the primary care physician. In MD Levine et al., eds., Developmental-Behavioral Pediatrics, 3rd ed., pp. 69–79. Philadelphia: W.B. Saunders.

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