(Corrects spelling to "Shawn" from "Sean" Carter in paragraph 17)
By Piya Sinha-Roy
LOS ANGELES, Feb 13 (Reuters) - Beyonce is letting fans into her charmed life, introducing daughter Blue Ivy to the world and talking about motherhood, marriage and miscarriage in a new documentary.
The 31-year-old pop singer and her rapper husband, Jay-Z, 43, one of music's most influential couples, have been guarded about their private life.
But in "Life is But a Dream," airing on Saturday on cable channel HBO, Beyonce gives fans a glimpse of her working life and even a peek at baby Blue Ivy, who has been fiercely shielded from paparazzi since her birth in January 2012.
The "Crazy in Love" singer addresses the widely reported claim from 2011 that she was faking her pregnancy, calling it "the most ridiculous rumor I've ever heard of me."
"To think that I'd be that vain ... especially after losing a child. The pain and trauma from that just makes it mean so much more to get an opportunity to bring life into the world," she says in the documentary.
The Grammy-winning singer shows footage of a sonogram, her growing bump and grainy video of herself posing nude as she neared her due date.
The HBO film, which Beyonce co-directed, is part of a return to performing by the singer, who took a year off after her first child was born.
The arrival last year of Blue Ivy Carter gained worldwide media attention and prompted Beyonce to share more with her fans, launching a Tumblr page with snapshots that showed glimpses of her family life, including the baby.
Her miscarriage had been kept secret from the public until Jay-Z referred to it in his song "Glory," that he released following the birth of Blue Ivy.
In the documentary, Beyonce touched on the topic briefly, saying, "It was the saddest thing I've ever been through."
"My life is a journey. ... I had to go through my miscarriage, I believe I had to go through owning my company and managing myself ... ultimately your independence comes from knowing who you are and you being happy with yourself," she said.
"Life is But a Dream" serves as a coming-of-age for the star as she entered motherhood.
She gives audiences a peek into her four-year marriage to Jay-Z, showing footage of the couple singing Coldplay's "Yellow" to each other.
"This baby has made me love him more than I ever thought I could love another human being," she says.
The documentary shows Beyonce putting herself and her team through grueling choreography rehearsals in 2011 and planning every second of her performances at big awards shows that year.
Beyonce began her comeback with a controversial lip-synched performance of the national anthem at President Barack Obama's inauguration in January, followed by a live performance at the Super Bowl halftime show that wowed critics.
She has also announced a new album for this year. "The Mrs Carter Show World Tour" - Jay-Z's real name is Shawn Carter - will kick off in April with more than 40 performances in Europe and North America.
"Life is But a Dream" airs on HBO on Saturday, the same day as Beyonce's interview with Oprah Winfrey on the OWN cable channel. (Reporting By Piya Sinha-Roy, editing by Jill Serjeant and Doina Chiacu)