Harry and Meghan have also asked the public to donate to four children's charities - Little Village, the Lunchbox Fund, Well Child, and Baby2Baby - instead of sending presents for the baby.
"The baby is a little bit overdue so we've had a little bit of time to think about it".
As congratulatory messages pour in from all over the world, including Australian Prime Minister Scott Morrison, questions have turned to the baby's name and his title.
Prince George, 5, is the eldest child of the Duke and Duchess of Cambridge, and the great-grandson of Queen Elizabeth II.
"The Duke and Duchess look forward to sharing the exciting news with everyone once they have had an opportunity to celebrate privately as a new family".
This Monday, May 6, William, 36, and Kate, 37, reposted Meghan Markle and Prince Harry's "It's a boy" image on their Kensington Royal Instagram account.
Meghan was a USA actress before marrying Prince Harry a year ago at Windsor Castle.
Speaking to the press, Prince William said he was "thrilled", while Kate said she is looking forward to finding out the little boy's name.
Homeland Security steps up use of biometrics data on border
Trump wants asylum-seekers to pay a fee to apply for the humanitarian status, among other new regulations he is proposing. Border Patrol agents are immigration officials, which is a prerequisite requirement to be considered an asylum officer.
The gushing prince addressed the media outside the stables at Windsor and spoke about how awesome witnessing the birth was and that both Meghan and the baby are doing well.
Writing on her lifestyle blog, Meghan told how her "free-spirited clinical therapist" mother took her to visit the slums of Jamaica and to see poverty in Mexico when she was just 10.
"I haven't been at many births".
In Prince Harry's case, the Queen didn't change the rules again to allow his children to be referred to as His or Her Royal Highness and a prince or princess.
Ms Ardern said New Zealand would make a donation to a group which prepares baby boxes for families in need and the Wellington government will buy native trees to be planted in New Zealand.
Betting odds for the names could change in the days leading up to the announcement.
"My mother raised me to be a global citizen, with eyes open to sometimes harsh realities", she said.
Details beyond where the Duchess hoped to have the birth were never discussed by the royals, who wanted their new baby to be delivered with utmost privacy.
"I've had about two hours' sleep", Hello! reports the prince as saying.
After testing multiple names, some came up with the theory that Arthur, Alexander, or James are being considered.