The students wore matching T-shirts with the message, "Abortion is homicide" but the April 21st coordinated event drew the ire of school administrators.
Kristen Norman told WTOL-TV the Anthony Wayne High School students were ready to stand up for their free speech rights until school officials kept adding more and more threats.
"We were told we could take the shirts off, turn them inside out or face a two-day suspension," Norman said.
The students refused and were then threatened with missing out on senior events.
"We were told we would not be able to go to our senior prom, would not be able to participate in senior skip days, go to a senior picnic or walk at graduation," Norman told the television station.
The Anthony Wayne school district refused to comment to WTOL-TV and officials did not respond to an email from LifeNews.com seeking comment for the story.
Senior Jamie Pellek said the students would pursue legal remedies if the school follow through on the threats.
"If they do not do anything else to change their decision... it could lead to legal actions," she said.
Erik Whittington of Rock for Life, which sponsors the shirts the students wore, said the school officials handled the matter poorly.
He said he didn't agree with "the decision to make Anthony Wayne High School students hide the pro-life messages on their T-shirts."
"The way this high school handled this situation is completely over the top. I am so thankful that these students went to the press," he added. "I highly doubt any other students at this high school will have any problems wearing pro-life T-shirts. Way to go guys."
Whittington has said in the past, when students at other schools were harassed by officials for wearing pro-life shirts, that his group would help students find legal representation from pro-life law firms to stand up for their rights.