I have always handled it with privacy and do not disclose any info without permission from the student, as this is how we handled it in the ER as well. I *encourage* the student to tell her parents, and I let her know that if she wants me/counselor to discuss with the parent then I will. I would never force them to tell their parents. However, under FERPA laws I believe, parents are entitled to school records upon request... I think the counselors can disclose to parents without issue, as long as the pregnancy is not a result of suspected abuse.
In Texas, if they are under 17 and elect to have an abortion, the doctor is required to notify a parent. So after I feel them out for what direction they're taking with their pregnancy, I may let them know this.
Title IX laws are federal laws regarding pregnant students.
Here is some info I found for my state: