The mother of one remained in a military hospital for five nights before returning to the White House on May 19 to recover, and wasn't seen for almost a month.
Her absence sparked endless rumours, with some believing her illness was used as an excuse to cover up the fact she had moved back to Trump Tower in New York with 12-year-old son Barron, or had undergone a facelift.
Despite the rampant speculation, White House staff refused to release any more information about Mrs Trump's illness, operation and subsequent recovery in order to protect the First Lady's privacy.
But the First Lady's body double rumours first went viral back in October 2017, after actor and comedian Andrea Wagner Barton posted her theory on Facebook.
Will the real Melania please stand up?
Is it me or during his speech today a decoy “stood in” for Melania??...
Posted by Andrea Andi Wagner on Friday, 13 October 2017
Those who believe in the theory cite the First Lady's changing appearance as "proof", while some have also pointed out a secret service agent with an uncanny resemblance to Mrs Trump.
According to the theory, Mrs Trump has a body double who takes her place at public events at certain times, and it has been fuelled by her penchant for sunglasses, clothing and accessories that often cover part of her face.
But the First Lady isn't the first celebrity to be accused of using a decoy.
In 2016, there were claims Hillary Clinton had been replaced by a body double and even a hologram after she collapsed at a 9/11 memorial service in New York after a battle with pneumonia.
And earlier this year, some theorists claimed a bizarre video of Meghan Markle appearing to "glitch" was evidence the now Duchess of Sussex had been replaced by a robot.
