Telling your new employer your pregnant

Angelina • Daughter: Stella renee. August 6th 2012. Son: Azrael jack-michael January 30th 2016, New baby coming March 2018
I just got hired at a home health agency for pediatrics. I'm 11w3days and idk if I'm should tell my new boss I'm pregnant. I mean do I ever have to tell them or is it ok for them to find out when I start to really show. This is my dream job. I've been wanting to do pediatrics since I passed my nursing boards. Need advice, I'm worried.