.DELTA.6-Retroprogesterone 152-62-5 6-Dehydro-9.beta.,10.alpha.-progesterone 6-Dehydroretroprogesterone 9-.beta.,10.alpha.-Pregna-4,6-diene-3,20-dione 9.beta.,10.alpha.-Pregna-4,6-diene-3,20-dione Diphaston Dufaston Duphaston Duvaron Dydrogesterone Gestatron Gynorest Hydrogesterone Isopregnenone NSC92336 Pregna-4,6-diene-3,20-dione, (9.beta.,10.alpha.)- Prodel Retro-6-dehydroprogesterone Retrone Retroprogesterone, 6-dehydro- Terolut