Meghan made her name in acting as savvy paralegal Rachel Zane in the USA television legal drama "Suits", a world far removed from Buckingham Palace.
Rumors are quickly circulating regarding potential names for the new addition to the Royal family.
After the performance, Harry and Meghan met with well-wishers outside the famed building, many of whom had been waiting for hours in the Sydney sun to catch a glimpse of the royal couple.
Instead, royal experts said if it's a boy, the child would officially be styled the Earl of Dumbarton - one of Harry's subsidiary titles - and Lady Windsor if a girl.
Meghan has also talked about wanting to have children.
"I've always coveted the Cartier French Tank watch", she said.
The royal couple started dating in July 2016 after they were introduced by friends, and Harry courted Meghan on a trip to Africa shortly afterward. "Prayers for them in the months ahead".
The Duchess's father previously raised hopes of an imminent Royal baby, noting that Meghan had wanted to be a mother for a "long time".
"She said that's really cool and she really liked the teddy bear".
It was another step in Harry's coming-of-age.
Dasha nodded shyly, before handing over her bouquet to Meghan.
"Here's your first gift for the nursery", Cosgrove told the couple during the official welcome at Admiralty House.
Meghan, the 37-year-old Los Angeles-born former actress from "Suits", and Prince Harry, the 34-year-old son of Prince Charles and Princess Diana, married on May 19 amid much fanfare, with 29 million viewers in the US and 18 million viewers in the United Kingdom tuning in.
Before their meet-and-greet, Meghan and Harry enjoyed a performance by the Bangarra Dance Company at the Sydney Opera House, having travelled to the iconic landmark via ferry from Taronga Zoo.
However, if it's a boy, Mullins gave the photo Harry's blue eyes.
Harry, who served with the British Army for a decade, including two tours of duty in Afghanistan, set up the Invictus Games after visiting the US Warrior Games in 2013. The games open on Saturday.
Meghan and Harry, proud parents-to-be, are thought to have shared their news with the royal family including the Queen, Prince Phillip and Prince Charles at the royal wedding on Friday which would suggest there's some truth to the 12 weeks estimate.
The children and grandchildren of the queen are princes and princesses - that's why Harry has that title - but this doesn't apply to great-grandchildren. She also traded in high heels for kitten heels instead.