OMG and WTF: Stevia was once used as an Anti-Fertility Agent?

Marco here ! Do tell... Perhaps it's not so sweet. I find it pretty shocking to find a passage where the authors excitedly discuss using stevia rebaudiana — the same sweet leaf hailed everywhere today as a wonderful, healthy sugar alternative — as an anti-fertility agent. What's more, it had apparently been used traditionally by indigenous Indian populations in Paraguay for a long time, and rats in studies had shown a large drop in fertility after being administered stevia... Could it be? Well, in any case, I'm not worried. I can't get pregnant anyway.