Queen Elizabeth Turns 89 As She Awaits Fifth Great-Grandchild

As she waits to welcome her fifth great-grandchild, Queen Elizabeth has notched another milestone.

The British monarch turned 89 on Tuesday, and begins a landmark year leading up to her 90th birthday.

She is said by aides to be “spending it privately” at home at Windsor Castle, about 30 miles west of London.

The Queen tends to always have her birthday at the castle with husband Prince Philip, 93, and she may be seen out horse riding there Tuesday. Members of her family may also pop in to see her and share some birthday cake, palace insiders say.

But the Queen, and the nation, will mark her birthday in more celebratory fashion in June, when the Trooping the Colour event – a ceremonial military exercise – takes place in central London.

By then, of course, she and the family will have more to celebrate with the addition of another great-grandchild – Prince William and Princess Kate’s second child. The child will join brother George, 21 months, and cousins Mia Tindall, 15 months (the daughter of Zara and Mike Tindall), and Savannah and Isla Phillips, ages 4 and 3 (the daughters of Peter and Autumn Phillips.)

Sentimentally, lots of gamblers have been betting on William and Kate’s new baby arriving Tuesday, and being a girl named Elizabeth.

Although she has nothing in her public diary, the Queen will still receive her “red boxes” of diplomatic and political papers she must read as head of state.

The landmarks continue this year. In September, she is set to become the longest-serving British monarch of all time, passing Queen Victoria’s record of 63 years and 216 days.

This article originally appeared on People.com.