Contraceptive properties of Stevia rebaudiana.
Stevia rebaudiana Bertoni (Compositae) is a Paraguayan weed containing a sweet substance called stevioside. It has been used as a hypoglycemic drug although this effect has not been confirmed. Matto Grosso Indians have used a decoction of dry powdered leaves and stems of the plant as an oral contraceptive. 90-152 day old albino rats were used to investigate the effect of a decoction of Stevia rebaudiana on fertility. The decoction was made by boiling the dry powdered weed in water for 10 minutes and filtering after cooling. A group of 14 rats each drank 10 ml of a 5% decoction daily. Another group of 14 served as controls. After 12 days for 28 females were mated. The decoction therapy was continued throughout the 6-day mating period. Males did not receive the decoction. After 50-60 days without therapy the females were mated again. In a 2nd experiment 14 rats were allowed to bear 1 litter each. A week after weaning, the same dosage for the same period was given and mating was repeated. After a recovery period of 50-60 days without therapy they were again mated. In a 3rd experiment 14 rats were first allowed to mate. A week after the litters were weaned the same dosage was given for 12 days and then they were mted. Fertility was reduced 57-79% in rats drinking the docoction as compared with controls. A reduction of 50-57% in fertility was still present at 50-60 days after intake of the decoction. In the 1st experiment 11 of the young, belonging to different litters, lost their tails without apparent cause at ages of 12-15 days. This did not occur in the other experiments.