According to the latest edition of US Weekly magazine:

Beyonce Knowles better brush up on her lullabies. The 29-year-old singer is pregnant with her first child, the new Us Weekly reports. Despite the happy news, no one was more surprised than the singer herself.
"B was shocked. She loves kids, but she wasn't ready to be a mother just yet," says a source of the singer, who married rapper Jay-Z in 2008. "She really wanted to get her album done and tour the world again."
Still, another insider says that the singer, who is in her first trimester, realizes that "this is a gift from God and she's so happy." Friends of the couple are already expressing their well-wishes for the parents-to-be. "Jay has been all about family since I met him, and he's always going to be," record executive Kevin Liles, who has known the rapper for years, tells Us. "I wish them the best." Knowles' sister Solange -- and mom to Julez, 6 -- agrees. "She's got the most beautiful heart," she tells Us of her big sis. "She'll be a great mom."

UPL wishes the happy couple well!

UPL UPDATE: Yesterday, Tina Knowles denied this rumor about her daughter's pregnancy. Denial is pretty common when it comes to celebrities so we'll just have to wait and see...