Sex steroid hormones are known to influence heart repolarization. Overall, estradiol is considered to promote QTc lengthening while progesterone and testosterone shorten QTc. New findings suggest more complex regulation of QTc by sex steroid hormones involving also follicle-stimulating hormone, which is associated to prolongation of QTc. Another important aim of this study is to study the influence of sex hormones on QTc duration.