So all we know for sure is that something happened in Gloucester, Mass.

What that something was depends on whom you believe. Last week, on its Web site, Time magazine quoted Gloucester High principal Joseph Sullivan as saying that, of 17 girls who became pregnant during the school year, nearly half did so as part of a “pact” to have and raise their babies together. Sue Todd, president of a group that runs a day care at the school, told Time she had heard a similar story from a social worker.

Officials reportedly became suspicious when an unusually high number of girls began showing up at the school clinic for pregnancy tests. Many who tested negative seemed crushed at the news. Those whose pregnancies were confirmed celebrated with high fives.

But on Monday, Gloucester Mayor Carolyn Kirk and school superintendent Christopher Farmer held a news conference to deny the supposed pact, saying there is no evidence any such agreement was ever made. Sullivan, according to Kirk, was “foggy in his memory.”

The principal was not at the meeting to answer for his allegedly faulty memory – Kirk said she was not “comfortable” having him there – and has declined to comment about the matter since the Time report, as has Sue Todd.

Frankly, it sounds as if the mayor and the school’s chief, faced with embarrassing international attention, are trying to cover their municipal backside by silencing and undermining the principal and the child care provider; it’s hard to believe Kirk and Farmer would know more about what was going on in Joseph Sullivan’s school than Joseph Sullivan did.

But the alleged pact is not what is most important here. These facts, after all, are not in dispute: 17 girls got pregnant; at least some of them did so on purpose; this represents more than a fourfold increase over the year before.

The Gloucester story unfolds in the context of troubling recent news about teen sexuality. In March, a federal study reported that one in four American girls between the ages of 14 and 19 – and nearly half of all African-American girls in that same age range – are infected with at least one of four sexually transmitted diseases: human papillomavirus, chlamydia, genital herpes and trichomoniasis. In June, the Centers for Disease Control and Prevention reported that a steep decline in teen sexual activity through the 1990s leveled off between 2001 and 2007. And after years of decline, the teen birth rate rose by 3 percent between 2005 and 2006.

Some will seek to blame this disturbing news on “Juno” or Jamie Lynn Spears, but the trends predate both. They do not, however, predate the Bush administration’s abstinence-only policy, which requires that any groups or states receiving federal funds for pregnancy prevention may not discuss contraception and must teach that sex outside marriage will lead to harmful psychological and physical effects. In other words, they cannot talk about sex or help children who do have sex to protect themselves. They can only tell them to say no.

Who can argue against saying no? What parent isn’t pro abstinence? But abstinence only? Anyone who thinks a teenager will never do a thing because she has been forbidden has never met a teenager. Common sense – and a 2007 study by the National Campaign to Prevent Teen and Unplanned Pregnancy – tell us abstinence-only does not work. But since when does President Bush let common sense and fact trump ideology?

Gloucester, Mass., is an aberration, but it might be an omen, too. And if it is, if these troubling numbers prove the leading edge of a new teen baby boom, we will have to answer many tough questions, but one won’t be tough at all.

We already know where it started. We already know who the father is.