The long wait for the royal baby continues.

Catherine, the Duchess of Cambridge, was admitted to a London hospital in the early stages of labor shortly before 6 a.m. local time (1 a.m. ET), a palace official confirmed. Her husband, Prince William, was at her side.

"Things are progressing as normal," a spokesperson for Kensington Palace told NBC News.

More than 12 hours later, no birth had been announced, and the world kept their eyes on the front door of St. Mary's Hospital (click here for a live feed from the scene).

Even President Obama had something to say. In his White House briefing, spokesman Jay Carney said that "like so many Americans, the president, first lady, and the entire first family wait with anticipation for the birth of the Duke and Duchess' child, and wish the family and all of Great Britain well on this pending momentous occasion."

According to NBC's Jim Maceda, photographers reported seeing royal vehicles at a back entrance to St. Mary's Hospital at about 6 a.m. local time. About 90 minutes later, royal officials confirmed Duchess Kate, 31, traveled from Kensington Palace to the Lindo Wing of the hospital in a car, not an ambulance.

The Lindo Wing is where Princess Diana gave birth to Prince William in 1982 and to his brother, Prince Harry, in 1984. The birth will be overseen by a medical team that includes Marcus Setchell, 69, the Queen's former gynecologist, and her current gynecologist, Alan Farthing.

Duchess Kate will also be assisted by several midwives and a member of the senior nursing staff, according to NBC News royal expert Camilla Tominey.

There are no plans for Duchess Kate's mother and sister to join her in the delivery room, Tominey revealed early Monday. "Buckingham Palace denied rumors that they were going to be in the delivery room with Kate. She very much wants just her husband to be there."

Though the queen had remained at Windsor Castle, she returned to Buckingham Palace shortly before 11 a.m. ET. There has been no announced change to her plan to leave Friday for a vacation at Scotland's Balmoral Castle.

The baby's uncle, Prince Harry, remained at his military base in eastern England.