One student gave birth Thursday.
The news has shocked the mainly Catholic community of Gloucester.
The girls confessed to making the pact after the school began investigating a rise in pregnancies among the 1,200 high school students. Normally, there are about four pregnancies a year at the school.
The school's principal says the first red flag came when a large group of teenage girls went to the school's clinic to ask for pregnancy tests. By May of this year, the nurse had already administered 150 of those tests.
The principal also says some girls even celebrated when the results came back positive.
"It's their choice; whatever they want to do. You won't catch me getting pregnant in high school. No way," said Gloucester student Mollie Wagner.
All the pregnant girls are 16 of age or younger.
"Many of the young women don't see direction and purpose in their lives. Many of them, I think, see themselves as not having a loving relationship necessarily," said Gloucester Schools Supt. Christopher Farmer.
One of the fathers is reportedly a 24-year-old homeless man.