That is what the FDA has used as an excuse for not approving Stevia for some time, but the fun thing is that the they have not done a study regarding Stevia's effect on the reproductive system. Those 'concerns' are taken from off-hand notes from other studies. In other words, they were studying any carcinogenic properties of stevia, and had 10 or so rats in their study, and the researcher off-handedly mentioned that one of the rats didn't get pregnant. They weren't trying to impregnate it, they never even mentioned if it did, etc, but it was an off-hand mention.
The reason it is held up is just an industry-protectionist thing in the US. We don't grow stevia natively, and a lot of artificial 'chemical' sweetener producers would lose a lot of money if their product lines became an anathema.
Besides, Stevia actually has the opposite effect on blood sugar that sugar does, in other words, for people who are diabetics... it helps them.