Hm, I think smoothies have fruit by definition (unless you want to substitute sweet veggies instead).

On the other hand, given that my midwives told me to eat smoothies made with whole fat yogurt and ice cream as well as the fruit (when I hit the heartburn stage I had trouble gaining enough weight to suit them), I expect that you could probably make something like a milkshake - a chocolate yogurt milkshake? Don't know if that gives you any inspiration.

You could also go for non-sweet things. Yogurt with fresh mint? Yogurt blended with raw spinach?

Blended soups might also suit the situation. Butternut squash soup with cream?