Swearing Off Sex: Can Bristol Palin Stick by Abstinence Pledge?

If Bristol Palin is truly going to abstain from sex until she's married, as she promised in front of millions of viewers last week on the "Oprah Winfrey Show," she has her work cut out for her, experts say.

Teen moms such as Palin, 19, say it can be done, but statistics show that most teens who pledge abstinence abandon the vow within five years.

"Many of these kids who do pledge to remain abstinent do so in the classroom with their peers. It's a group event, so there's a lot of peer pressure," parenting contributor Ann Pleshette Murphy told "Good Morning America" today. "Not probably as much as being on Oprah.

VIDEO: Is premarital sexual abstinence a realistic goal for teens?Play

"I think the point was, it is very hard," she said.

The oldest daughter of former Alaska Gov.Sarah Palin renewed her pledge to remain celibate until marriage, despite Winfrey's offer for her to "retract" the vow on national television.

"I'm just wondering if that's a realistic goal," Winfrey said.

"It's a realistic goal for myself," Palin said.

Alisha Tew knows firsthand how difficult Palin's abstinence pledge can be to keep. She has stood by her own pledge for four years, ever since the birth of daughter Miley shortly after her senior year in high school.

"You never think that is going to be you who finds yourself in that situation and going to be a teen mom," Tew said. "For me, the hardest thing was how I was going to be a great mother, but still be a 19-year-old."

Four years after making her celibacy vow, Tew will walk down the aisle in May.

"When you really go through the experience and know how difficult it is, and the strength you need to have this baby in your life, than it makes it worth it to just wait," she said.

But not everyone can keep that kind of vow. A Columbia University study that followed 12,000 teens found that 88 percent of those who made an abstinence pledge had sex before marriage and had similar rates of sexually transmitted diseases to those who didn't take a pledge. They were also much less likely to use contraception.

"Abstinence works when it is used consistently and correctly," Monica Rodriguez, vice president for training and education for the Sexuality Information and Education Council of the United States, told "Good Morning America. "The problem is that abstinence isn't always used correctly, and when it fails, it has a really high failure rate."

Murphy said the reason the numbers are so high for abstinence-only kids not using contraception is because of the education they are getting.

"Abstinence-only programs, for the most part, don't teach you how to use protection," she said, suggesting that what's needed is a comprehensive education that encourages kids to wait while teaching them how to use contraception if they change their minds.

And that kind of education should start, she said, at home. Discussing contraception, she said, does not equal giving teens permission to have sex.

"Parents are the most important people in kids lives in terms of this," she said. "You have to share your values."

Palin became pregnant while still a high school student, and she has become a vocal advocate for teaching teenagers that they should practice abstinence rather than safe sex to avoid becoming pregnant.

Oprah Winfrey Admits She 'Bristled' at Bristol Palin's Abstinence Pledge

Winfrey told Palin she "kind of bristled" when she learned the teen recently told In Touch magazine, "I'm not going to have sex until I'm married. I can guarantee it" and wondered if such a promise was "realistic."

The talk show host told the teen mom, who appeared on Winfrey's show alongside her mother that she was likely setting herself up to fail and asked if she regretted making such an absolute pronouncement.

"Why set yourself up that way? It may be 10 years before you get married. Why set yourself up so that everybody you go out with, you date -- the media is going to be looking at that person, trying to get that person to sell you out, to say, 'Did you have sex or not,'" said Winfrey. "It's nobody's business when you chose to have sex."

Palin gave short answers to Winfrey's queries, saying, "No, I don't," to a question about whether she felt she was setting herself up to fail at keeping her abstinence pledge.

Winfrey told Palin she was "going to give you a chance to retract or ease that statement if you wanted to and not say categorically, 'I'll never have sex until I'm married.' But if you want to hold to that, may the powers be with you. So you're going to hold to that?"

But before Bristol Palin could answer, her mother asked a surprising follow-up question.

"Does that mean you're going to marry pretty young?"

Her daughter mumbled a response, "I don't know, Mom."

Palin, the former Alaska governor who recently took a job as a Fox News analyst, said she was not encouraging Bristol to get married.

"I'm telling her, don't think she has to find a man and marry young. The world is her oyster, and she's going to be able to pursue an education and career and avocation opportunities without a man," said Palin.

Bristol Palin's pregnancy was made public within days of John McCain's announcing he had chosen Sarah Palin as his running mate in the summer of 2008.

She was briefly engaged to the baby's father, Levi Johnston, whom she has recently taken to court to get full custody of their son, Tripp, and ask for increased child support.

Bristol Palin is seeking $1,750 a month from Johnston, according to court documents filed Thursday and reviewed by The Associated Press.

The documents say Bristol Palin is providing nearly 100 percent of Tripp's care, and that Johnston has paid only $4,400 in more than a year.

Rex Butler, Johnston's lawyer, told the AP that his client had tried to give Bristol Palin money for the baby's care on several occasions, but she refused to meet him.