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Posted by Dr. Monica Wonnacott | January 9, 2016

When Puberty Starts: Girls vs. Boys

Stages of puberty for girls:

Typically girls show signs of puberty 2 years earlier than boys.

  • Thelarche (breast development), adrenarche (pubic hair development), pubarche (growth), menarche (first period/menses)
  • The average age for greatest growth/height velocity in a girl is 12.1 years old (with a range of 10.4-13.9 years).
  • It is normal for a girl to start her period somewhere between the ages of 9 and 16.

Stages of puberty for boys:

  • Enlargement of the testes, lengthening of the penis, appearance of pubic hair, physical growth
  • The average age for greatest growth/height velocity in a boy is 14.1 yrs old (with a range of 12.2-15.9 years).
  • Average age of onset of puberty is 12 (ranges from 9 to 13 for onset)
  • Gynecomastia (swelling of the breast tissue) is very common concern during puberty, occurring in approximately 60% of adolescent males.

What is delayed puberty?

Puberty is delayed if there are no signs of secondary sexual characteristics by the age of 13 in girls and 14 in boys.

What is precocious (early) puberty?

Precocious puberty is the early onset of what are called secondary sexual characteristics (e.g., breast development, pubic hair, or armpit hair) before the age of 8 in girls and 9 in boys.