I doubt I would use batiks for a baby quilt without washing the fabrics first. Aside from the issue of bleeding, these are fabrics that are not "manufactured" in a traditional manner, and may still have a good deal of chemical residue . I have noticed on many occasion when I am steam pressing a noticable distictive odor in the fabric.
So best, if you a making a baby quilt, to play it safe on all issues and prewash the fabric.
Oh one more note... They do tend to fade quicker than most fabrics.