If Princess Kate has her baby in the middle of the night, don't expect to know until daylight.
That's the advice of palace insiders as any announcement that Kate, 33, has given birth likely won't be made between around 10 p.m. and 8 a.m. GMT.
That's because of the understandable desire to inform the people in both families before the outside world is told.
Last time, Kate entered the Lindo Wing of St. Mary's hospital in Paddington, London, shortly after 5 a.m. GMT but her being in labor wasn't confirmed until 7.30 a.m. GMT.
Before any official announcement is made, Queen Elizabeth II, who turns 89 on Tuesday, and members of both families will have to be informed and "processes like that can take some time," a palace source says.
"I wouldn't think anyone will be waking the queen before 8 a.m.," adds a royal source.
When Prince George was born in July 22, 2013, the couple waited for around four hours to tell the media. They were enjoying the special moment of bonding with their child, and phoning family and their closest friends to tell them the news.
And there is every possibility that if Kate is admitted to hospital in the middle of the night, she could have their child before any announcement is even made that she has been admitted and been in labor.
Staff at the palaces say they will be constantly reviewing the advice and guidance they give to journalists, so that the guidelines laid out at palace briefings could change.
This time any announcement will be made in an email to journalists and then Tweeted from the official Kensington Palace Twitter account a few minutes later.
The announcements will be confined to Kate being in labor and then that she has given birth.
Keep reading PEOPLE.com for more on the royal birth.