The first lady had been scheduled to re-emerge in the public eye late Monday at a private reception for families of United States soldiers killed in action - her first public appearance since being hospitalized last month.
Shortly afterwards, she entered Walter Reed National Military Medical Center for what the White House described as a benign kidney procedure. Four days later, the White House said in a statement that she had undergone a successful embolization procedure.
During the White House event for Gold Star families, President Trump alluded to the speculation, according to reporters in the room.
It will be Mrs Trump's first official engagement in weeks, though the event is private and closed to news media coverage.
Melania Trump's absence from the public eye has been particularly perplexing to some considering that she announced her "Be Best" anti-bulling initiative on 7 May.
Ever since, her absence has been noticeable - and she even pulled out of attending a presidential retreat with her husband over the weekend.
Israel says troops kill Palestinian attacker in West Bank
The resolution drafted by Kuwait, the only Arab member of the Security Council, had undergone numerous revisions in recent weeks. The meeting echoed Kuwait's call for an emergency session when Israeli soldiers killed dozens of Palestinians on May 14.
"Good to see her doing so well" added Greene. Some wondered whether Melania was holed up with the Obamas while others suggested she had packed her bags and returned to NY because she was fed up with life at the White House. Comedian John Oliver joked that an oversized letter the president received from North Korea was actually from Melania.
The White House had said gave no official reason for Melania Trump not going on this trip. Mrs. Truman also spent a lot of time in Missouri with her mother.
In the USA families of U.S. military members who died in battle are known as Gold Star Families.
She is known for her privacy and White House independence, often breaking with her husband's schedule.
The first lady's attendance at such events is normal and several of Ms Trump's predecessors have hosted them.
Before the reception, amid ongoing memes and questions about her boss, Ms Grisham said the "nonsense" was fuelled by the media.
During a press briefing Monday, Press Secretary North Korea announced the US will not remove its sanctions and may even increase its maximum pressure campaign if denuclearize talks fail.