Hair growth on a woman's chin or neck may be caused by the menopause or other premenopausal conditions, such as polycystic ovary syndrome. Such conditions lead to excessive production of male sex hormones, such as testosterone, dehydroepiandrosterone and androstenedione. However, in around 25 percent of women with hirsutism, there are no apparent causes.
Polycystic ovary syndrome, or PCOS, is the most common cause of hirsutism by far. It is a condition in which small cysts develop around the ovaries.
Less common premenopausal conditions associated with hirsutism include Cushing's syndrome, tumor, obesity and congenital adrenal hyperplasia. Whatever the cause, hirsutism is not particularly uncommon among women, with around 15 percent affected.