Sexual Development of Girls

Girls go through five stages of development during puberty.

Girls usually start to show the physical changes of puberty between the ages of 9 and 13, which is slightly sooner than boys. The female sex hormone called estrogen and other hormones cause the physical changes.

Many girls are fully developed by the age of 16. Some girls will continue to develop through age 18.

Here are the five stages and what happens:

Stage 1: Between ages 8 to 12 .

• No visible signs of physical development. But the ovaries are enlarging and hormone production is beginning.
  
  

Stage 2: May begin anywhere from ages 8 to 14.

• Height and weight increase rapidly.
  
  
• Fine hair growth begins close to the pubic area and underarms.
  
  
• Breast buds appear; nipples become raised and this area may be tender.
  
  
• Sweat and oil glands become more active which can result in acne.
  
  

Stage 3: May begin anywhere from ages 9 to 15.

• Breasts become rounder and fuller.
  
  
• Hips may start to widen in relation to waist.
  
  
• Vagina begins secreting a clear or whitish fluid.
  
  
• Pubic hair becomes darker, thicker, and curlier.
  
  
• Height and weight continue to increase.
  
  
• For some girls, ovulation and menstruation (periods) begin, but may be irregular.
  
  

Stage 4: May begin anywhere from ages 10 to 16.

• Underarm hair becomes darker.
  
  
• Pubic hair starts to form a triangular patch in front and around sides of genital area.
  
  
• The nipple and the dark area around the breast (areola) may stick out from the rest of the breast.
  
  
• For many girls, ovulation and menstruation (periods) begin, but may be irregular.
  
  

Stage 5: May begin anywhere from ages 12 to 19.

• Adult height is probably reached.
  
  
• Breast development is complete.
  
  
• Pubic hair forms a thick, curly, triangular patch.
  
  
• Ovulation and menstruation (periods) usually occur regularly.
  
  
• Overall look is that of a young adult woman.
  
  

To learn more about girls and reproduction, check out Female Reproductive System. For additional information, visit Menstruation and Reproductive Health Care and Pregnancy.

Last revised: March 27, 2009