1. Contraceptives, Oral, Synthetic Oral contraceptives which owe their effectiveness to synthetic preparations. 2. Contraceptives, Postcoital, Synthetic Postcoital contraceptives which owe their effectiveness to synthetic preparations. 3. Luteolytic Agents Chemical compounds causing LUTEOLYSIS or degeneration. 4. Menstruation-Inducing Agents Chemical compounds that induce menstruation either through direct action on the reproductive organs or through indirect action by relieving another condition of which amenorrhea is a secondary result. 5. Abortifacient Agents, Steroidal Steroidal compounds with abortifacient activity. 6. Hormone Antagonists Chemical substances which inhibit the function of the endocrine glands, the biosynthesis of their secreted hormones, or the action of hormones upon their specific sites. | 
