WASHINGTON (AFP) - US President Barack Obama and his family are waiting "with anticipation" for the birth of Prince William and his wife Kate's first child, the White House said on Monday.

"Like so many Americans, the president and first lady and the entire first family, you know, are - wait with anticipation for the birth of the duke and duchess' child," spokesman Jay Carney told reporters.

The Obamas "wish the family and all of Great Britain well on this pending momentous occasion," Carney said.

The Duchess of Cambridge was admitted to hospital early Monday, but there was still no news for the hundreds of international media camped outside.

The baby will be third in line to the throne and in the direct line of succession after Queen Elizabeth II's eldest son and heir Prince Charles, and then his eldest son William.