A sudden baby boom among students at Gloucester High School here has taken town officials by surprise. An investigation has revealed that the 17 high school girls expecting babies are part of an apparent teenage "pregnancy pact."

School officials became suspicious in early October after an unusual number of girls began filing into the school clinic to find out if they were pregnant. After questioning, nearly half the expecting students, none older than 16, confessed to making a pact to get pregnant and raise their babies together.

The number of pregnant teenage girls in 2008 is more than four times the number of pregnancies the 1,200-student school had last year. Most of the fathers did not attend high school and one has been identified as a 24-year-old man.

Massachusetts law states it's a crime to have sex with anyone under the age of 16.

The school reportedly carried out 150 pregnancy tests to students in the past academic year.

Adults in Gloucester variously blame a depressed local economy, broken families, adrift children, difficult access to birth control and hit movies like "Juno" and "Knocked Up" that they say glamorize pregnancy to young audiences.

Some even blame the trend on celebrities such as Jamie Lynn Spears, the 17-year-old sister of Britney, who gave birth to a baby girl on Wednesday.

The nation's teenage pregnancy rate increased in 2006 for the first time in 14 years, according to the most recent figures from the US Centers for Disease Control and Prevention.