The cause of
polycystic ovary syndrome (PCOS) is not fully
understood, but genetics may be a factor. If you have PCOS, your sisters and
daughters have a 50% chance of developing PCOS.1
The first signs of PCOS are usually after a
girl's menstrual cycle begins (menarche). A teen with menstrual periods over 45
days apart may need to be seen by a doctor to make sure she doesn't have PCOS.
(Normally, the first periods and ovulation are hard to predict. They become
regular within the first 2 years after menarche. For more information, see the
Normal Menstrual Cycle.) In some women, PCOS starts
after a big weight gain.2, 3
PCOS problems are caused by hormone changes.
One hormone change triggers another, which changes another. This makes a
"vicious circle" of out-of-balance hormones in your
endocrine system, including:
- Ovary hormones. When the hormones that trigger
ovulation are not at the right levels, the ovary does not release an egg every
month. In some women, cysts form on the ovaries. These cysts make
- High androgen levels. High
androgen in a woman causes male-type hair and acne problems and can stop
- High insulin and blood sugar levels. About half of
women with PCOS have a problem with how the body uses insulin, called
insulin resistance. When the body doesn't use insulin
well, blood sugar builds to high levels. If not treated, this can lead to
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