 It has been said that the lack of ovulation inhibition and hyperthermic effect with retroprogesterone derivatives like dydrogesterone may represent a dissociation of peripheral and central progestogenic activity.However, a related retroprogesterone derivative, trengestone, likewise does not inhibit ovulation or produce a hyperthermic effect but rather has an inducing effect on ovulation.Whereas all other assessed progestins are associated with an increased risk of breast cancer when combined with an estrogen in postmenopausal women, neither oral progesterone nor dydrogesterone are associated with a significantly increased risk of breast cancer (although the risk of breast cancer is non-significantly higher with dydrogesterone).