What Causes Ovarian Cysts?

Irregular menstrual cycles
Hormonal imbalance
Hypothyroidism
Cigarette smoking
Early menstruation (11 years or younger)
Increased upper body fat
Infertility treatment with gonadotropins, this may cause multiple large cysts.
Use of Clomiphene (Clomid, Serophene) has been shown to increase the risk for development of Corpus Luteum cyst.
Use of Tamoxifen for breast cancer