Estrogens mediate their contraceptive effects in combination with progestins by inhibiting ovulation. Unlike other medications like progestins and anabolic steroids, estrogens do not have other hormonal activities. Appetite stimulants include glucocorticoids, cannabinoids, or progestins such as megestrol acetate. A large number of progestins, or synthetic progestogens, have been derived from progesterone. They are formulated both alone and in combination with progestins such as medroxyprogesterone acetate. Long-term use of oral contraceptives with highly potent progestins can also induce endometrial atrophy. Certain other progestins act similarly in this assay, whereas progesterone acts neutrally. However, the medication shows less androgenic activity than related 19-nortestosterone progestins like levonorgestrel and norethisterone. Menstruation can be delayed by the use of progesterone or progestins. Progesterone lacks undesirable off-target hormonal activity, in contrast to various progestins. Changes in breast density with progesterone appear to be less than with the compared progestins. A few progestins have weak estrogenic activity. This effect is caused by the ability of some progestins to inhibit androgen receptors. Dienogest is one of the only 19-nortestosterone derivative progestins that does not have androgenic properties. The relative glucocorticoid activity of MPA is among the highest of the clinically used progestins.