The McCain-Palin campaign says it’s for change, and it certainly delivered change with its abrupt abandonment of the long-standing conservative view of teen pregnancy. For decades, religious conservatives in the Republican Party pointed to teen pregnancy as a troubling sign of moral decay. But when the McCain-Palin campaign announced that Governor Sarah Palin’s unmarried seventeen-year-old daughter was pregnant, the party’s operatives went into a huddle and emerged with an expediently different view: Teen pregnancy is just one of the challenges of middle-class family life.

The Republican declaration drew swift and scornful charges of hypocrisy and political opportunism from the Left. It fell to socially liberal journalists to lecture Republicans on the problems associated with unmarried teen pregnancy. Columnist Joe Conason called upon the Palin camp to “stop pretending this is good news,” and went on to cite the standard social-science litany of problems associated with teen pregnancy: school drop-out, low-birth-weight babies, more infant illness, increased likelihood of failed marriages among the relatively few who wed.

As it happens, this flare-up in the political world occurs at a crucial moment for teen-pregnancy policy in the real world. Beginning in the early 1990s, the teen birth rate began to drop and continued to fall for the next fifteen years without an increase in abortion. The most recent statistics, however, tell us that the teen birth rate has begun to rise again: it increased by 3 percent between 2005 and 2006.

Perhaps this one-year increase will prove to be a short-term blip and the rate will settle back to the levels of the recent past. But there is some reason to believe that the rate may remain at the new level and possibly increase further. Back in the early ’90s, the premise was that the teen birth rate was high because teenagers were ill-informed or misinformed about sex. Religious prohibitions and Victorian inhibitions, it was thought, prevented kids from getting a complete and accurate view of the facts of life. Thus, the public policy consensus at the time was the schools should provide this information to all students, and both approaches to sex education—abstinence-only and comprehensive—as different as they are in other respects, did exactly that. Both sides engaged in frank discussions about sex, contraception, and the best way of preventing teen pregnancy. Both increased sexual awareness for all but the most sheltered teens. Both, most experts agree, played a part in the fifteen-year decline in teen pregnancy. Today, however, each of these approaches may be reaching the limits of effectiveness.

What limits the effectiveness of abstinence-only education is the profound change in the early-life-pattern of young women. The span of time between the two classic benchmarks of “growing up” has gotten much longer. Girls reach puberty at younger ages than girls did in the past, but they reach social maturity—the completion of schooling, entry into the workforce, and marriage—at much older ages. Biological change occurs slowly, but social change has been much faster. The median age of a woman at marriage is now close to twenty-six-and higher for college graduates.

Sexual abstinence used to mean waiting just a few years between high school graduation and one’s wedding day. Now it often means abstaining from sex for a decade or more. Obviously, this is much harder to do, not only because the time period is longer but also because marriage usually comes last in the sequence of events that young adults now associate with growing up. Today fewer people who marry in their late twenties have managed to remain abstinent. And the expanded period of sexually active singlehood increases the risks of parenthood among the unwed.

Comprehensive sex education has a different limitation. It assumes that a teenaged girl who knows about contraception and has ready access to it will indeed use it if she decides to have sex, because she will want to avoid pregnancy and motherhood. But this assumption doesn’t apply to those girls who know about contraception and have access to it, but don’t use it because they want to have a baby at a young age. In short, the comprehensive sex-education approach fails to take into account some teenage girls’ desire for someone to love. And babies, as it happens, are easier to have and hold on to than boyfriends. Teen motherhood also gives girls who have few other opportunities for recognition and achievement a positive role and identity. Then too, pregnancy itself brings baby showers, special school programs for parenting teens, the excited attention of friends. And babies are, of course, lovable and life-changing. Ethnographic studies find that teen motherhood gives some girls a sense of purpose and drive to succeed against the odds. Lastly, baby mamas are the new celebrities. Paparazzi have turned from stalking Paris Hilton at nightclubs to trailing sixteen-year-old Jamie Lynn Spears through Baby Gap.

What happened recently in the Massachusetts fishing port of Gloucester is an example. There, fourteen high school girls became pregnant in a single year, a sharp jump from the three such pregnancies in the year before. Though these girls didn’t form a “pact” to get pregnant, as originally reported, it does appear that they got pregnant deliberately. By all accounts, the Gloucester teens knew how to prevent pregnancy and where to get condoms. They simply wanted to become moms.