By Piya Sinha-Roy
LOS ANGELES (Reuters) - Beyonce is letting fans into her private 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 guarded their privacy fiercely.
But in "Life is But a Dream," airing on Saturday on cable channel HBO, Beyonce gives fans a glimpse of how she works and even a peek at baby Blue Ivy, who has been shielded from paparazzi since her birth in January 2012.
The film, which Beyonce co-directed, is part of a return to performing after a year off since her first child was born.
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.
At the New York premiere of the documentary on Tuesday, the new mother said she wanted to share her altered perspective on life.
"Knowing that at this point in my life, this age is so wonderful because I see everything differently and I hope that I can share that with other people," she said.
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 HBO film shows footage of a sonogram, Beyonce's growing bump and grainy video of herself posing nude as she neared her due date.
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 of her family life.
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" also gives a peek into the Grammy-winner's four-year marriage to Jay-Z, showing 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 film 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 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.
(Additional reporting by Alicia Powell at Reuters TV in New York, editing by Jill Serjeant and Doina Chiacu)