The seventeen schoolgirls are pregnant going into the summer holidays at the 1,200-pupil Gloucester High School in Massachusetts, 30 miles north of Boston.
"Nearly half the expecting students, none older than 16, confessed to making a pact to get pregnant and raise their babies together," Times Online quoted Joseph Sullivan, the headmaster, as saying.
Sullivan said he suspected that the girls were influenced by Hollywood.
One of the fathers is a 24-year-old homeless man, and others are also in their mid-20s.
All of the pregnant girls are under 17 and some are younger than 16, the age of consent in Massachusetts, prompting the mayor to ask about possible criminal charges for under-age sex.
"At the very least these men should be held responsible for financial support, if not put in jail for statutory rape as the mayor has suggested," Greg Verga, the chairman of the Gloucester School Committee, said.
School officials became suspicious when girls began seeking pregnancy tests at the school clinic and seemed more upset when they were not pregnant than when they were.
Some girls reacted with high-fives and started planning baby showers when they learnt they were expecting.
After administering about 150 pregnancy tests, the medical director and the nurse at the school clinic recommended prescribing contraceptives to pupils regardless of parental consent. The idea went down badly with families in the predominantly Roman Catholic town and the two clinic staff resigned in protest on May 30.
Christopher Farmer, the schools superintendent, said: "The common threat is the lack of self-esteem and purpose in life, and a lack of a sense of direction. Young women wanting and needing affection."