Darker colours on the cake are intense and may stain the hands and teeth. They are however removable within a few washes.
They may also result in the buttercream tasting slightly bitter, so just a slight note on that.
On top of that, while we use the highest quality food colouring imported from the U.S.A. and is 101% food safe, some babies under 1 year may still react to it (eg. Mild rashes).
What we recommend instead is to opt for pastel or lighter colours! We use just enough white mixed into our cakes to look pale and soft while maintaining its colorful personality.