Tatiana Alejo, a counselor, at a class on teenage pregnancy.

“It is well past time when anyone can afford to be value-neutral when it comes to teen pregnancy.”

— The mayor’s press office

The New York Times – In the South Bronx, inside the International Community High School, Johnny, Brayan, Khady, Genesis and Francisco link arms and joke and giggle and write out lists of what they admire about each other. Sometimes they hug.

They are working-class kids, ninth-graders navigating the shoals of adolescence. Each is a volunteer in a program, Changing the Odds, aimed at decreasing the likelihood that they will become teenage parents.

They hear no didactic lectures and see no wagging fingers. There is patient trust-building, and an insistent message: It is hard enough to escape poverty’s fierce gravitational pull; to add to that the grueling business of raising a baby makes it harder still.

“You try to give them a safe place to talk,” says Tatiana Alejo, 26, a counselor with the program, which shows great promise. “They have so many social pressures. And we never, ever, downgrade or shame.”

This is the day-to-day reality of the campaign against teenage pregnancy. Mayor Michael R. Bloomberg, personally and through his health and education departments, takes a vibrant role in this movement. Teenage pregnancy remains a perilous problem but has dropped sharply in the city and across the nation in the past 20 years.

You wonder, is Mr. Bloomberg aware of this?

I ask, as last week his administration began a jarringly judgmental advertising campaign that aims to shame teenage parents and scare teenage girls who are not yet parents by warning that really bad consequences await should they get pregnant.

One poster shows a weepy baby boy, staring at the camera, and these words: “I’m twice as likely not to graduate high school because you had me as a teen.” Another poster features a pensive toddler and states: “Honestly Mom … chances are he won’t stay with you.”

Like most parents, I have tumbled down the Class IV rapids that are raising teenage children. On a personal list of my stupidest moves, resorting to the shame-and-blame game ranks at the top.

Before State Senator Liz Krueger, Democrat of Manhattan, took a bungee jump into politics, she was among the city’s wisest thinkers on poverty. Her bottom line is clear: Spending scarce money on a “scared straight” campaign is “fatally stupid” and likely to backfire.

The Bloomberg administration did not waste much time arguing last week. Marc La Vorgna, the mayor’s press spokesman, typed out a Twitter post: “We’ve been criticized for edgy, aggressive public service ads, but we’re not stopping.”

“Edgy” sounds cool, sort of like the décor at the Brooklyn Nets arena, or wearing your baseball cap backward at brunch. “Edgy” works less well when adults try to talk at teenagers.

Two months ago, Robert Doar, commissioner of the city’s Human Resources Administration, gave this subject a test run. He delivered a speech to the Manhattan Institute, a conservative policy group, in which he lamented that President Obama “almost never turns his hypercritical eye” toward single-parent families.

Mr. Doar, whose agency finances this campaign, took a poke at the “leaders of the groups where the problem of single parenthood is most severe, both the African-American and Hispanic communities.” They “refuse to take this issue on aggressively,” he said, “or deal with it in any meaningful way.”

I’m not sure which church pew Mr. Doar sits in, but when from time to time I find myself in black and Latino churches, I often hear a social message that is usefully middle-class, and aimed at encouraging men and women to recognize their responsibilities to one another. And black, Latino and white legislators rake in tens of millions of dollars to underwrite the city’s programs aimed at breaking the cycle of teenage pregnancy.

As for Mr. Obama, himself the son of a single mother, he has invested many millions of dollars to battle teenage pregnancy and fought to include contraception in his health plan. Contraception, study after study shows, plays a central and inescapable role in pushing down the number of pregnant teenagers.

There is a conceit, widely held among Mr. Bloomberg’s inner circle, that this city administration alone speaks truth. But mayors long ago recognized teenage pregnancy as a crippling problem of poverty.

In 1991, Mayor David N. Dinkins and the schools chancellor, Joseph A. Fernandez, fought for the right for high schools to distribute condoms. Mr. Bloomberg picked up the cudgel when he announced that selected schools would distribute Plan B, an emergency contraceptive pill.

The politics are rough. But no less rough than learning to speak to teenagers in a language they respect.

Estelle Raboni grew up in a Dominican family in Washington Heights and directs Changing the Odds. Teenage girls have babies, she says, in pursuit of something understandable. They want to love, and to be loved.

Parenthood sometimes provides a balm. But the cost — in education deferred, income lost and isolation — is great.

“It’s so much more complicated than telling a teen: ‘Don’t do it’ or ‘Your boyfriend will leave you,’ ” Ms. Raboni says. “Fear cannot motivate a girl who already feels alienated.”

That registers as a value-sensitive bottom line.