No, no, no. That's a bit like calling the doctor to change a nappy! Children's minds are NOT fragile. In fact, they're far more resilient than most of the grown-ups turned pop psychologists who constantly transfer their own fears and thoughts onto them.
Children love nothing better than to get their teeth into a good story. If you want to write for them, sit down, write, have lots of fun and enjoy it. Use your common sense. If you're talking sex and drugs, then it's probably not a children's picture book! If you're in doubt, you'll get plenty of help here by sharing a section and letting the experts have a look. Agents and publishers will also make sure you're pitching to the right age group so don't worry too much about it. Write what you think they'll enjoy, following all the same rules (if there's such a thing) as writing for adults - plot, conflict, resolution, etc. etc.
Good luck,
Symphony