This is the one thing Meghan Markle is banned from doing on her birthday

And we're not sure what to think...

Meghan Markle turns 37 this week, seeing in her first birthday as a royal on Saturday. But how will she celebrate?

Well, like most elements of Meghan's life as a Duchess, there are rules and regulations.

Yes, while having a royal title gives access, opportunity and of course the luxury of living in a palace, there is also a lot of duty that comes with the role, and a hefty rulebook to follow.

From wearing tights and not wearing black, to a ban on shellfish and tracksuits, Meghan has been brushing up on all royal rules and guidelines in her Princess lessons, and it seems that her birthday is no exception.

In fact, there is even a royal rule especially focused on birthdays, with the now Duchess banned from doing one particular thing as she welcomes in the big 3-7.

What can't she do? Have a lavish party.

Yes, really. According to tradition, royals are not supposed to have big parties, and should instead have small family celebrations - a change from the kind of Hollywood celebrations Meghan is no doubt used to.

Either way, we're sure Harry will have planned something special for the big day.

Last year, the prince whisked Meghan off on a safari in Botswana, so it's going to be a hard celebration to follow from home.

We hope Meghan has a very happy birthday.