Definition of Female pattern baldness:

Female pattern baldness involves a typical pattern of hair loss in women, due to hormones, aging, and genes.

Causes, incidence, and risk factors:

A hair grows from its follicle at an average rate of about 1/2 inch per month. Each hair grows for 2 to 6 years, then rests, and then falls out. A new hair soon begins growing in its place. At any time, about 85% of the hair is growing and 15% is resting.

Baldness occurs when hair falls out and normal new hair does not grow in its place. The reason why new hair does not grow in female pattern baldness is not well understood, but it may be related to:

• Aging
• Changes in the levels of androgens (male hormones). For example, after reaching menopause, many women find that the hair on their head is thinner, while the hair on their face is coarser.
• Family history of male or female pattern baldness

Hair loss can occur in women for reasons other than female pattern baldness, including the following:

• Breaking of hair (from treatments and twisting or pulling of hair, or hair shaft abnormalities that are present from birth)
• Certain skin diseases that lead to scarring of the hair follicles
• Hormonal abnormalities, such as too much testosterone, or too much or too little thyroid hormone
• Iron deficiency
• Medications such as chemotherapy and beta blockers
• Patchy hair loss (alopecia areata)
• Syphilis
• Temporary shedding of hair (telogen effluvium) after a major illness, surgery, or pregnancy
• Vitamin deficiency (such as biotin)