adjective /ˌpiː.diˈæt.rɪk/ /ˌpiː.diˈæt.rɪk/ (Cambridge Dictionary) There is no rules without exception, so I would recommend you look up online dictionary to ensure your pronunciation is clear and proper. As soon as you are confused with certain pronunciation, you must check the proper one, which is often shown clearly in the formal dictionary. I would have to say even some of the native speakers are not sounding well in regards to the standard pronunciation in the dictionary.

Google them: forvo, merriam webster and cambridge dictionary. These sites are quite useful when we talk about pronunciation.

For pronunciation questions online dictionaries are your best best. Either those, or Forvo. For UK English, Oxford or Cambridge Dictionaries, for US English, Merriam Webster. Anyway, for pediatric (spelt 'paediatric' in British English) the pronunciation is the same in both US and British English. https://www.merriam-webster.com/dictionary/pediatric https://en.oxforddictionaries.com/definition/paediatric Not quite what you had, the pronunciation is actually 'Peed-eeh-ah-tric'. The pronunciation is also the same for 'psychiatrist.' https://en.oxforddictionaries.com/definition/psychiatrist https://en.oxforddictionaries.com/definition/psychiatrist By the way, the word is 'pronounce'. 'Pronounciate' doesn't exist.

I'm so sorry it took so long to say this, but I really appreciate your time. I perfectly agree with you that it's not a typical 'ia' example and it's probably because it's the medical term, which comes from latin or greek a lot. It's one of the very confusing parts in studying medical terms, because, not only the spelling is different but also is the pronunciation! Thanks again.

Actually, this word is strange because the first syllable is "Pee," not "Ped." So it's "pee-dee-atr-ic." The 'a' is prounced like 'apple.' This is not a typical "ia" example, so it isn't necessarilly pronounced like others, probably because it's based in latin or greek (it's a medical term).