“It’s another reminder that great storytelling can be a powerful catalyst for change,” says Stephen K. Friedman, the president of MTV. By all accounts, the MTV shows worked because they focused on compelling stories, not on lecturing or wagging fingers.

“If the government tried this, it would have a good message, but three people would watch it,” Professor Levine said.

Middle-class Americans tend to think of contraception in terms of condoms or pills, but just as critical is a girl having a prospect of a better life if she delays childbearing. Kearney and Levine find that one of the factors in the long-term decline in teenage births is the improvement in job possibilities for women.

For example, girls who were randomly assigned to attend Promise Academy, a middle school in Harlem Children’s Zone, were less likely to become pregnant because they were also more likely to excel and have a shot at college.

As a haughty journalistic scribbler, I tend to look down on television, so it’s a bit painful to acknowledge its potential for good. But the evidence is overwhelming.

A careful study by Robert Jensen of the University of California, Los Angeles, and Emily Oster of the University of Chicago found that before television arrived in Indian villages, traditional attitudes ruled: Women had to get a man’s permission to leave the house, and 62 percent of women said it was acceptable for husbands to beat wives. Then villagers watched Indian soap operas with middle-class urban families in which women aren’t beaten and leave the home freely. These norms infiltrated the village, and the arrival of television turned out to be equivalent, in nurturing more egalitarian attitudes, to five years of female education.

The master of injecting causes into storytelling is Neal Baer, the television producer behind “ER” and “Law and Order: Special Victims Unit.” Baer, a doctor who helps lead the Global Media Center for Social Impact at U.C.L.A.’s school of public health, wove issues like vaccination and rape-kit testing into his shows, raising awareness in ways that no news program could. Polling showed that one “ER” episode about cervical cancer doubled the audience’s awareness of links between the human papillomavirus and cervical cancer.

Some more good news. After a hiatus, MTV will introduce season five of “16 and Pregnant” on April 29. Family planning clinics had better stock up!