First official and public appearance since allegations of infidelity emerged

First Lady Melania Trump made a very visible return to the public stage on Tuesday by attending her husband's maiden State of the Union address.

This is her first official appearance since accusations of infidelity surfaced about the president.

Donald Trump's enigmatic wife emerged publicly for the first time since she fed the Washington rumour mill by cancelling her trip to Davos, Switzerland, leaving him to attend last week's World Economic Forum on his own.

Melania's no-show in Davos came on the heels of a bombshell report that Trump had a fling with porn star Stormy Daniels in 2006, just months after his wife gave birth to their son.

But for Trump's big night in Congress, Melania arrived smiling and waving, to warm and extended applause - dressed in a crisp cream white pantsuit that stood in contrast to the black donned by Democratic lawmakers in solidarity with the victims of sexual harassment.

Minutes later, her husband took the floor and exchanged waves with his wife.

Among Trumps' guests in the first lady's box were a US Marine corporal who stepped on an explosive device and lost both legs while deployed in Iraq in 2007; first responders who helped save hurricane victims in Louisiana and Texas, and parents of children killed by the gang MS-13.

Breaking with tradition, the first couple arrived separately to the Capitol, because, according to the first lady's spokesperson Stephanie Grisham, she was accompanying guests.

Afterwards, the first lady was seen being escorted out of the gallery by a military officer, as Trump spoke with lawmakers and administration officials on the House floor.

It was not immediately clear whether the Trumps returned together to the White House.

As the 47-year-old wife of a 71-year-old man known for past lewd remarks about women, and whose two past divorces became public spectacles, Melania is dogged by speculation that they lead largely separate lives.