"I think you have to let them follow their dreams. I think it would be worse in the end if you didn't," Spears, 53, told People magazine in an interview marking the publication next week of her much-anticipated memoir.
As Britney's star rose, Spears said she felt she was losing control over both her daughter and how she was portrayed.
"I let other people talk me out of things that I felt a gut instinct about," she told People.
The memoir "Through the Storm: A Real Story of Fame and Family in a Tabloid World," is published by Thomas Nelson, a Christian publisher of bibles and inspirational books.
It chronicles Spears' family during the phenomenal rise of Britney Spears in the late 199Os and her highly publicized meltdown.
Originally planned for a May release, the book was postponed in January after Jamie Lynn Spears, then 16, announced in a celebrity magazine that she was pregnant.
"I simply did not have the huge ambitions for (Britney) that I have been accused of," she writes. "Much has been written about how we were counting on our daughter to rescue us from financial ruin. Ha!"
Despite an estrangement that meant she watched on television the ordeal of Britney shaving her head in February 2007 and being taken to the hospital in hysterics last January, Spears said that Jamie Lynn's pregnancy was the hardest time of her life.
Spears writes that she was shocked, angry and saddened when Jamie Lynn, whom she had thought was a virgin, broke the news by handing her mother a note which read "Mama, I'm pregnant. I'm going to keep the baby and everything is going to be okay."
The former star of the Nickelodeon teen TV hit "Zoey 101" gave birth in June to a girl and is now raising the baby with her boyfriend in their Mississippi home.
"Every mother makes mistakes and I'm no different," writes Spears, who has been harshly criticized in the media for her parenting skills.
Spears said she first felt she was losing control in 1999 when Britney, then 17, appeared on the cover of Rolling Stone magazine in her underwear. She said the magazine photographer had taken Britney into her bedroom alone during the shoot.
"When I saw the cover, my heart sank and my face burned," wrote Spears, who quit her teaching job in 2002 to join Britney on tour.
Spears, who has been criticized for parenting skills, told People she "wanted the truth out in her own words for myself and my family."
In the past nine months, Britney's father has taken over management of her affairs, she has settled a bruising divorce and child custody battle and is working on her sixth album, which will be released in 2009.
