Duchess Kate and Prince William's baby will have plenty of company in royal family

From left, Sophie, Countess of Wessex, and her son James, Viscont Severn Severn;and daughter Lady Louise Windsor disembark the Hebridean Princess with other members of the Royal Family in Scrabster Harbour on Aug. 2, 2010.
Chris Jackson

The baby that Prince William and Kate, the Duchess of Cambridge, are expecting will have lots of company in the palace nursery.

St. James' Palace announced the pregnancy Monday, saying that Queen Elizabeth II and other members of the royal family were "delighted" by the news. The baby will be the third great-grandchild of the queen and Prince Philip, Duke of Edinburgh, and the fourth child under age of 6 in the immediate royal family.

Prince William's cousin Peter Phillips and his Canadian wife, Autumn Kelly, have two daughters: Savannah, born Dec. 29, 2010, and Isla, born last April. Phillips is the son of the queen's daughter, Princess Anne.

Prince William's uncle, Prince Edward, Earl of Wessex, also has young children. His daughter, Lady Louise, was born on Nov. 8, 2003, and his son, James, Viscount Severn, is the queen's youngest grandchild, born Dec. 17, 2007. Louise was among the bridesmaids at William and Kate's April 2011 wedding.

In terms of succession, William and Kate's baby will outrank them all, becoming third in line behind William and his father, Prince Charles. Right now -- and the baby's arrival will change this -- Viscount Severn is eighth in the order of succession, followed by Lady Louise in ninth place. The Phillips girls are 12th and 13th in line for the throne.