Kate Middleton

(PHOTO) REUTERS/Neil Hall

Kate Middleton recently sparked pregnancy rumors during an outing with Prince William and reports claim the royal couple is hoping for a baby girl.

On Dec. 11 the Duke and Duchess of Cambridge attended the screening of Sir David Attenborough's "Natural History Museum Alive 3D" in London and onlookers claim Middleton, 31, cradled her stomach throughout the event. The couple welcomed the birth of their first child in July and sources believe she may already be pregnant again with baby number two.

"She looked absolutely beautiful and glowing, and her hand rested only on her stomach for most of the night," an alleged eyewitness told Star magazine.

"There was definitely what seemed to be a little bump showing already. And William was so tentative to her, quietly whispering to Kate and asking if she wanted to sit down or needed a sip of water. It was so sweet," the source revealed.

The couple raised questions about a second pregnancy in October when they remodeled their four-story 20-room Kensington Palace apartment to include a second nursery in addition to the one made for their 5-month-old son, George Alexander Louis.

While royal officials are yet to address recurring pregnancy rumors, insiders claim Middleton is in fact three months along.

"Their immediate families [were] obviously thrilled beyond words when the couple told them news," a source revealed.

"The other royals, including William's grandmother, Queen Elizabeth II, were let in on Kate's wonderful secret during their Christmas lunch at Buckingham Palace on Dec. 18 - and the entire family is now sworn to keeping it quiet so that an official announcement can be made in the New Year," the source explained.

The couple is already considering baby names and sources claim Diana is a top pick if they do in fact have a baby girl.

"Kate's mum Carole Middleton, has already been pushing for the baby to be named after William's late mother, Diana, as a beautiful tribute," the source said.

"But Kate and William would also consider Elizabeth or Philippa. If it's a boy however, they're thinking Charles, Henry, Philip or Spencer," the source added.