After steadily dropping for a decade, the US teenage sex rate leveled off in 2001 and has stalled there since, according to a government study. What caused the halt in the trend is unclear, but it coincides with the beginning of increased funding for abstinence-only sex education and may reflect more relaxed attitudes among teens to the dangers of AIDS.
Experts worry that the plateau could precede a dramatic rise in teen sex similar to that of the '70s and '80s, bringing with it higher teen pregnancy rates. "It is alarming," said one expert. "For it to level out causes everyone to go, 'Uh-oh.' " But another expert said the statistics might simply show "how hard it is to change basic human behaviors." (Read more teenager stories.)