The pregnant woman facing removal from the UK was given a wheelchair to assist her in the departures area of the Cedars centre in Pease Pottage, West Sussex, inspectors said.
But when she resisted "substantial force" was used by G4S staff and the wheelchair "was tipped up with staff holding her feet".
"At one point she slipped down from the chair and the risk of injury to the unborn child was significant," the report said.
"There is no safe way to use force against a pregnant woman, and to initiate it for the purpose of removal is to take an unacceptable risk."
More top news
Samples from 95 buildings in 32 local authority areas have failed fire safety tests - 100% of the cladding samples submitted.
But which member of the royal family spends the most?
The web giant must pay £2.1bn, the European competition watchdog has ruled.