The formation of the important major steroid hormones from cholesterol occurs through intermediary formation of a steroid known as pregnenolone. Though it contains the cholesterol nucleus, pregnenolone has a shorter aliphatic side chain than the related substance. Pregnenolone is the precursor of progesterone, the female hormone that is dominant during pregnancy, and also androgens (or male sex hormones), such as testosterone. The estrogen female sex hormones, estrone and estradiol, and the adrenal corticosteroids, such as corticosterone, are also metabolic products of cholesterol.