I think criticism of a Catholic school firing a pregnant unmarried teacher is really misguided. People send their kids to faith-based schools to help them inculcate the values of their faith, and teachers are supposed to be role models. To have a teacher obviously violate it and still be in the school confuses kids. As a Hindu Brahmin (a sect that abhors the consumption of animals), I would be outraged to find out a teacher in a school of my faith did not adhere to those same principles!
Secular schools just have to have different criteria than faith-based schools ... actually make that true for all types of institutions!!