Although the decision to engage in premarital sex while employed by a Christian school was unwise (as I believe all premarital sex to be), the school had no right under existing HIPAA law to ask the question regarding the pregnancy. They can’t even ask that of a person when being hired.
It sounds to me that the staff and parents were engaged in gossip, and so the school decided to assuage that sin by releasing the medical information. There is a greater problem in that school than just this pregnancy.
She’s at fault for deception, but the school broke the law. No one wins in a case like this.
As someone pointed out earlier, schools don't fall under HIPAA. Doctors, health insurance companies, hospitals, etc all fall under that law, but the only thing a private entity deals with that would fall under that is your insurance information. There may be other claims, though it appears that she tried to assert those other claims already and lost.