"Congratulations to The Duke and Duchess of Sussex on this joyous news!" she added.
Enthusiastic fans were quick to comment on the snap, wit one person writing: "Awwww I love this and I love them! Congrats to the beautiful couple."
Another person stated: "Oh wow never thought photo shoots could be done remotely but of course they can- makes so much sense. Gorgeous shot."
Meanwhile, a third fan added: "Beautiful photo! I hope they have a peaceful pregnancy."
Prince Harry and Duchess Meghan's second child will make them a family of four - the pair welcomed their first son Archie Harrison back in May 2019.
Baby Sussex 2.0 will also be the fifth grandchild for Prince Charles and the tenth great-grandchild for the Queen and Prince Philip.
Following Archie's birth, the Duke and Duchess of Sussex revealed that their son wouldn't have a royal title and would simply be known as Archie Harrison Mountbatten-Windsor. Less than a year later, the pair announced they would be stepping back from their senior roles within the royal family.
That means their new baby boy or girl will follow suit with Archie, and likely grow up outside of the pressurised royal circle.
This is also likely to be the last Baby Sussex as Prince Harry revealed that he and Meghan would only have two children.
Speaking to celebrated ethologist Dr Jane Goodall in July 2019, Harry talked about the effects of humans on the planet, saying: "I've always wanted to try and ensure that, even before having a child and hoping to have children..." to which Jane interjected, saying: "Not too many!"
"Two, maximum!" Harry assured her at the time.
Traditionally, the gender of royal babies are not revealed before their birth but we have a hunch that Prince Harry would be keen for a little girl to join their family.
Shortly after Meghan's pregnancy with Archie was announced at the Sydney Invictus Games, the Duke of Sussex was attending the road cycling event when someone in the crowd called out to the red-headed royal, "Congratulations, I hope it's a girl!"
And in his typical down-to-earth fashion Harry replied, "So do I!"
Opening up about motherhood before she stepped down as a full-time working royal, Meghan admitted she was riding the highs and lows of the new gig.
"My goodness it's a lot, but it's all so exciting. There are days when it's a lot to juggle but then you meet someone and you have an impact on them and you say 'aha,' and it's so rewarding," she revealed when Archie was five months old.
Back when she was pregnant with Archie, Meghan managed to look utterly chic in every maternity ensemble she wore.
Whether she was sporting top designers such as Dior and Givenchy or rocking budget H&M and Marks and Spencers looks, the Duchess of Sussex proved she was one of the biggest fashion icons in the planet. And as her baby bump grew, she just continued to glow.
Bring on the return of maternity fashion!
This story originally appeared on our sister site Now To Love.