Daniel Sant, a spokesman for Lorde's booking agency, said Lorde was "under a lot of pressure" and it meant her commitments "shifted constantly and very quickly".
Sant said her US tour commitments had extended "above and beyond" what they had expected, meaning she had been forced to cancel some bookings. She had discussed touring Australia in April, but this now appears unlikely.
Her spot on the Gear Up line-up has been filled by Alpine and Miami Horror DJs. Other acts on the bill include San Cisco, Pond, Deep Sea Arcade, The Kill Girls and Bottlerockets.
Lorde is currently touring Australia as part of the Laneway Festival, and is set to perform with Disclosure at the Brit Awards on February 19.
She was forced to pull out of the Auckland leg of Laneway to attend the Grammy Awards, but held a make-up show for 10,000 fans at Silo Park two days later.
Lorde's American tour is completely sold out and is set to begin in March. The tour starts in Austin Texas and includes shows in Washington, Philadelphia, New York, Boston, Toronto, Detroit, Chicago and Seattle.
She is also due to perform at the Coachella festival.
- nzherald.co.nz