First lady Melania Trump's plane was forced to return to a Washington area military base on Wednesday because of smoke in the cabin.
Her spokeswoman, Stephanie Grisham, said "everyone is fine and everyone is safe" after the plane returned to Joint Base Andrews.
Mrs. Trump had been scheduled to visit a Philadelphia hospital and meet with families of children affected by exposure to opioids while in the womb.
Grisham said the first lady's team was "evaluating" whether to make other arrangements to travel to the event.
According to TV reporters traveling with the first lady, the flight was in the air about 10 minutes when smoke filled the cabin, and then Secret Service agents rushed to the front of the plane. Reporters aboard the plane noticed smoke in the cabin and were told to hold wet towels over their faces if it got worse.
The smoke dissipated and the aircraft returned without further incident.
It was not immediately clear what caused the problem.
The event was planned for Thomas Jefferson University Hospital, where Health and Human Services Secretary Alex Azar was to join the first lady. The hospital has provided care to mothers with opioid use disorder and their newborn children for more than 45 years.
Mrs. Trump was to tour a neonatal intensive care nursery and speak at an HHS conference on a new system that tracks infants suffering from opiate withdrawal.
The first lady's intended visit was to be one of stops as she promotes her "Be Best" campaign, which focuses on issues affecting children, including the importance of healthy pregnancies.