Last Updated May 2, 2015 6:54 AM EDT
Update: Kate has given birth to a baby girl.
LONDON -- Kate, Duchess of Cambridge, has entered the hospital to give birth to her second child with Prince William.
Kensington Palace released a statement Saturday morning saying Kate was admitted to the private Lindo Wing at St. Mary's Hospital in London at 6 a.m. (1 a.m. Eastern) in "the early stages of labor."
The royal couple made the short trip to the hospital by car and were at the hospital together.
The Lindo Wing, is where His Royal Highness Prince George of Cambridge -- or Prince George for short -- Kate and William's first son, was born just less than two years ago. Prince William and Prince Harry were also born there. Prince Charles was born at Buckingham Palace.
During her first birth, Kate entered the hospital at around 6 a.m., and the baby was born about 10 hours later. The first time around, she stayed in the hospital for just one night.
As with George's birth, the British royals will take a more modernized approach with the couple's second birth announcement, sending an email to journalists two minutes before posting the big news on Twitter. The official announcement is then placed on an easel outside of Buckingham Palace. This all happens after Queen Elizabeth II, senior royals and Kate's parents, the Middletons, receive the news first.
So where will the pending new addition fall in the line of succession? The baby, regardless of gender, will be fourth in line to the throne - essentially serving as the backup or "spare" if anything happens to the first-born in the family.
When George came into the world on July 22, 2013, he catapulted ahead of Prince Harry to become the third in line to the throne -- right behind his grandfather, Prince Charles, and his father, William. Kate and William's newborn is now fourth in line, pushing Harry to fifth place. Prince Andrew, Queen Elizabeth II's second son, now shifts to sixth in line to the throne.
In 2013, Britain changed a centuries-old ruling on gender that put boys before girls in the line of succession. Under the old system, a princess' succession spot could be replaced by a younger brother. Reports have said the royal couple do not know the baby's gender.
If they have a girl, it will be the first time a great granddaughter of a still serving sovereign has been born in direct succession on the male line since 1897, when George VI's sister Princess Mary came into the world.
There's been a lot of buzz surrounding William and Kate's second baby, but not nearly the media frenzy that surrounded their first-born child in 2013.
Kate's second pregnancy was announced on Sept. 8, but her due date remained a mystery. In March, she reportedly told a charity worker that she was due mid-to-late April, which is already a big month for the British royals: Queen Elizabeth II was born on April 21, and William and Kate's wedding anniversary is April 29.
Kate, 33, and William, 32, made plenty of appearances over the past several months, maintaining their official duties until March, with Kate looking quite fashionable at every stop.
In December, the royal couple came to the United States, where they visited the Sept. 11 Memorial and Museum, attended a black-tie gala at the Metropolitan Museum of Art and took in a Brooklyn Nets game. While there, they met Beyonce, Jay Z and LeBron James. In early March, Kate visited the set of "Downton Abbey."
During her tour of London's Ealing Studios, she met with "Downton" cast and crew members and watched a scene being filmed for the series' upcoming sixth season. Her final public appearance before giving birth took place at the end of March, when she and William toured a community center in South London. After that, she was spotted picking up a few last-minute items at Zara Home in Kensington High Street, London, just a short walk away from her home at Kensington Palace.
On April 28, she was spotted driving away from Buckingham Palace, where she reportedly took George for a swimming lesson in the palace pool.
Things were a little bumpier earlier on, with Kate experiencing hyperemesis gravidarum (severe morning sickness), the same condition she had during her first pregnancy with George. The morning sickness forced Kate to scrap plans for her first solo royal tour to Malta -- though she soon started feeling better and resumed her royal duties.
The Duke of Cambridge started paternity leave in April, taking a break from his new job as an ambulance helicopter pilot. He expects to begin flying rescue missions this summer, while continuing to maintain his royal duties and engagements.
Ahead of the birth, William and Kate sent boxes with croissants and pastries, along with coffee, to royal fans waiting in tents outside St. Mary's Hospital.
The former Kate Middleton and William got engaged in October 2010 during a trip to Kenya and were married in a lavish ceremony at Westminster Abbey on April 29, 2011.