My daughter had this same problem when she changed jobs when her son, our grandson, with CAH was 2 years old.  He is now almost 8.  She found out after alot of foot-work that no insurance company can deny coverage for children with CAH, nor can they institute a waiting period for coverage for children with CAH as long as there is no lapse in coverage between the original policy under which the child was insured to the new policy commencing.  This is the case here in the State of Va.,, so I would imagine other states/companies would follow suit.  Good luck to you