Happy birthday, ! Today the second eldest child of Prince William and Kate Middleton, and , turns three!

Traditionally, the Duke and Duchess of Cambridge have to celebrate their children's birthdays. This year, however, a photo of Charlotte , before her first day of nursery school, with a message wishing her happy birthday. The reason? The family just welcomed a new member, Prince Louis, just a few weeks ago, so they might be a little busy. They also may be planning to share a photo of the new baby with his siblings in the next few weeks.

"William and Kate won't want to overexpose their children," royal expert Penny Juror told . "They have never been entirely conventional so I imagine they might release a photo in their own time, and it might be one Kate takes herself."

So, until we get new photos of the royal family, take a look back at these adorable pics of Princess Charlotte, in honor of her third birthday.