The Duke and Duchess of Cambridge are extremely hands on parents to their three children, Prince George, Princess Charlotte and Prince Louis.
But, the royal couple were advised against having a third child soon before they announced they were expecting Prince Louis, who was born in April 2018.
Kate and Prince William had embarked on a royal tour towards the end of 2017 throughout Poland and Germany, and Kate was gifted a baby toy while greeting members of the public in Warsaw.
At the time, Prince George was four and Princess Charlotte was two so the toy was no use to either of them and Kate turned to Prince William and said: "We'll just have to have more babies," MyLondon reports.
Most would consider this an innocent joke between a married couple, however, an organisation called Having Kids spoke out shortly afterwards "respectfully" asking the Cambridge's to "consider forgoing having a third child."
The company's executive director president, Anne Green Carter Dillard, penned an open letter to the couple which read: "the example the British Royal Family sets is extremely influential," adding that they have the power to "make a sustainable small family."
"Of course, we know that Prince George and Princess Charlotte are certain to have wonderful lives, protected from the deprivations of poverty and the threat of environmental degradation," she wrote.
"They will receive optimal amounts of care and attention, as well as the best possible education. But the same can’t be said of every future child."
Anne went on to suggest that choosing not to have a third child would mean "substantial resources" were being "saved to help a different family plan a fair start in life for their child."
However, two months later, William and Kate announced they were expecting baby number three and on April 23, 2018, Prince Louis was born.
Since then, fans have regularly asked the couple whether they have any plans for a fourth child, and during their most recent trip to Northern Ireland, someone shouted: "Number four?"
Kate replied: "I think William would be a little worried," suggesting baby number four isn't on the cards - at least at the moment.
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