First of all, congratulations are in order for the birth of your niece.  Also, your sister is lucky to have a brother who cares so much and is concerned for her and the baby.  I have a 15 yr old girl with CAH and I can tell you she is a true joy.  Be assured that while CAH is a serious medical condition, it is one that is treatable. Your neice should have a completely normal childhood in terms of doing all the things kids like to do - with the exception of more doctor visits to monitor her and medications that have to be taken daily.  It does seem pretty overwhelming at first, but after a while, it won’t.

This board is good because you get to talk to parents of children with CAH and some adult CAHers and get their perspective on things and learn from their experiences.  Lots of times they can answer your questions from experience.  People on this board have lots of different opinions at times, but that helps too when you are trying to sort things out.

As far as other resources, the Cares Foundation (http://www.caresfoundation.org/) is a great place to go for info.  Another good one that I used A LOT when I was searching for answers several years ago is the Magic Foundation (http://www.magicfoundation.org/).  I know lots of references are made here on this board to Cares, which is great and I use it from time to time, but Magic is also good and has a great explanation/overview of CAH   (http://www.magicfoundation.org/divisions/cah.htm) and several other growth disorders. one of them being precocious puberty which is sometimes a problem with CAHer’s (http://www.magicfoundation.org/divisions/pp.htm). 

Good luck to your sister, her baby, and the rest of the family - and God Bless You for being there for her.