06/30/2008 05:12 am ET | Updated Nov 17, 2011

Psychology Of A Teen "Pregnancy Pact"

The disturbing news that a "pregnancy pact" among teenage girls at Gloucester High School has resulted in at least 17 of them becoming pregnant, with one of the fathers apparently a homeless man, has people asking how such a pact could have come about. ABC News examines the underlying psychology:

"Teen pact behavior -- whether to get pregnant or to commit suicide -- has the same underlying characteristics," notes Dr. Carole Lieberman, Beverly Hills psychiatrist and a clinical faculty member at UCLA. "The act the teenagers conjure up together is forbidden and self-destructive, and therefore must be kept secret..."

..."The members of the pact develop trust, camaraderie and rebelliousness by sharing this secret," Lieberman says. "These bonds then impel them to commit the forbidden act that they wouldn't have the courage to do on their own..."

..."There is no doubt that the media influence people -- consciously and unconsciously -- to copycat what is portrayed, whether it's to become violent or to become pregnant," Lieberman says. "Movies like 'Juno' or 'Knocked Up,' soap operas, and pregnant teen celebrities like Jamie Lynn Spears make teen girls believe that getting pregnant is cool, regardless of your age, and whether you love -- or even know -- the father."

The other element that some say may have come into play is the copycat factor -- a phenomenon in which young viewers imitate what they see in the media. One illustration of this principle occurred in 1993; some who had watched the film "The Program," imitated a scene in the movie in which high school football players lay on the center line of a highway to test their courage. One of these real-life imitators died after being struck by a car.