And now Prince William and Duchess Catherine are reportedly weighing up whether or not a third prince or princess is on the cards.
The Cambridges already share the chubby-cheeked angel that is Prince George, three, and their "joy of heaven" Princess Charlotte, two.
But at the start of May, their life was given a major plot twist when Buckingham Palace announced Prince Philip would be retiring from his royal responsibilities.
As the couple, who celebrated their six-year wedding anniversary on April 29, absorb more of The Duke of Edinburgh's state roles, insiders close to the pair claim they're seriously considering not adding to their brood due to their increasingly busy schedule.
“I would be very surprised if they have a third child," a source explained to The Sunday Express.
“They have got a boy and a girl – there is a sense that their family is now complete and they are moving onto the next chapter in their lives.”
Kate herself has spoken openly about the challenges and joys of raising children.
"Personally, becoming a mother has been such a rewarding and wonderful experience. However, at times it has also been a huge challenge, even for me who has support at home that most mothers do not" Catherine admitted recently of parenthood.
"Nothing can really prepare you for you the sheer overwhelming experience of what it means to become a mother. It is full of complex emotions of joy, exhaustion, love and worry all mixed together. Your fundamental identity changes overnight."
This August, Prince William will leave his part-time role as a helicopter pilot for the East Anglian Air Ambulance so he can become full-time royal and support The Queen.
The family-of-four have also relocated from their Anmer Hall estate back to Kensignton Palace in London.
However many royal watchers have dismissed the report and think one more mini-royal could happen.
"They want at least three kids and for them to be close in age," a well-placed pal told Vanity Fair last year before Prince Philip's retirement.
Indeed, the bookies still have them tipped to announce a third pregnancy in 2017 and they've even rounded up their top picks for names!
For those playing at home, Betfair reckon Arthur or Henry for a boy and Alice or Victoria for a girl.