Sweetners?

So I know there are a lot of different opinions on this but I want to hear them all, all I ask is for people to be kind to eachother in the comments. What are your guys' thoughts on natural sugar free sweetners like stevia, pyure, etc during pregnancy? I have heard mixed results about the effects as there are not a lot of studies in the medical world about it. My sisters doctor said no way, but my friends doctor said it was better than sugar and ok in moderation. I am trying to be healthy this pregnancy (as I am quite plus sized) and though I eat fruits etc with natural sugar, whenever I crave sweets, I would like to be able to give in once in awhile but don't want to eat super sugary foods. I can make most desserts substituted with stevia or some other sugar alternatives but just don't want to hurt the baby. PS: I don't use Splenda or sucralose due to the awful chemicals.