By JOCELYN NOVECK

AP National Writer

NEW YORK (AP) — One is a soft-spoken teenager who never sought fame, but was thrust into the national spotlight at the most delicate moment of her young life. The other is a glamorous pop star, a fixture in celebrity magazines and on countless iPods.

Bristol Palin and Rihanna have absolutely nothing in common — except that they are two young women whose private turmoil is currently playing out in the harsh glare of the public sphere.

Each has also, unwittingly, become the face of a pressing social issue — a source of teachable moments on teen pregnancy for Palin, domestic abuse for Rihanna. And each, despite all the public fascination, is having an experience that experts in those fields say mirrors that of thousands of ordinary young women across America.

Palin was already five months pregnant when she emerged into public view last year, clutching her baby brother as her mother, soon-to-be GOP superstar Sarah Palin, introduced herself to the world as John McCain's new running mate.

The pregnancy story soon broke, and campaign handlers rushed her boyfriend, Levi Johnston, a high school hockey player, to Minnesota. They appeared together on the Republican convention stage, and Sarah Palin said the two would soon be married.

In December, their son Tripp was born, and in a recent interview on Fox News, Bristol called Johnston a "real hands-on Dad." But this week, Johnston confirmed the couple had split "a while ago," and then things got ugly, with Bristol implying in a statement that her former fiance and his sister had been speaking to the tabloids for financial gain.

The breakup may have launched a thousand blog posts. But in the scheme of things it was a typical outcome, say experts on teen pregnancy.

"The notion that what has happened to Bristol Palin and Levi Johnston is unique is just not supported by the data," says Bill Albert, spokesman for the National Campaign to Prevent Teen and Unplanned Pregnancy. "Marriage among teens is extremely rare."

While half of teen mothers say they expect to marry the father of their child, Albert says, in fact fewer than 8 percent of them do within a year. And if teens do marry, that union is twice as likely to fail as that of a couple aged 20-25.

It's not clear in this case who left whom. In any case, "Bristol Palin and Levi Johnston were trying to accomplish something very few people successfully do — raise a child as teens," Albert says. "That's hard work in the best of circumstances."

In the blogosphere, there was the inevitable I-told-you-so response. "Did anyone think these two were going to get married? I saw this coming a mile away," was a typical post on urbanbaby.com, a Web site for mothers.

But there was also evident sympathy for Bristol Palin, who some assumed had been forced to get engaged in the first place.