Unwed teen mom Bristol Palin did a turnabout Wednesday with her views on teen sex, saying abstinence is a realistic option for teenagers. 

Palin, who gave birth to a boy four months ago, told ABC's "Good Morning America" that she wishes she'd waited to have sex. She said abstinence is a realistic way for teens to avoid unwanted pregnancy. 

"Regardless of what I did personally, I just think that abstinence is the only way you can effectively, 100 percent foolproof way you can prevent pregnancy," the 19-year-old daughter of Alaska Gov. Sarah Palin said. 

In a Feb. 16 interview with FOX News' Greta Van Susteren, Palin said that while teens should wait to have sex, advocating abstinence is unrealistic. 

"I think abstinence is ... I don't know how to put it ... everyone should be abstinent or whatever, but it's not realistic at all," Palin said at the time. 

Levi Johnston, Palin's former fiance and the father of her baby, Tripp, echoed that earlier view, saying Wednesday that abstinence is "not realistic" for young people. He said sexually active teens need to learn about contraception as well. 

"Abstinence is a great idea," Johnston told "CBS This Morning" in an interview. "But I also think you need to enforce, you know, condoms and birth control and other things like that to have safe sex. I don't just think telling young kids, 'You can't have sex,' it's not going to work." 

Johnston said he and Palin had used condoms but occasionally had slipped up. That's how Tripp was conceived, he said. 

Palin said Tripp is getting chubby and is starting to giggle. She called him "the love of my life," but said she wished she could have had him later in life.

The Associated Press contributed to this report.