What exactly are your concerns?

Avoid woods that have been treated for outdoor use and engineered woods such as OSB and MDF (that can off-gas).

Other than that, the only concern I can think of is irritation during sawing and shaping, or if there is any allergic sensitivity. For example, my daughter has allergic sensitivity to aromatic red cedar.

You want to use hardwoods, not building materials---like ply or furring strips.

Maple, walnut, oak, poplar are the easily obtained varieties.

I agree with handymac.Solid wood kids' bed frames tend to be the most appealing choices, because they are both sturdy and naturally attractive. Quality wood kids' bed frames will often utilize the natural beauty of the wood itself to create a stunning design in any kids' bedroom.