A premature baby girl needed testing for HIV after a hospital twice gave her breast milk from strangers.
Zene Yates, born eight weeks early and weighing just 3lb, was given the wrong milk through a tube while in the neonatal ward at Lewisham Hospital in south-east London. She was later sent home with bottled milk from a second stranger.
The first mistake was noticed by nurses while Zene was being fed, and her mother, Sarah Yates, discovered the second error when she was defrosting the milk.
A hospital spokesman said Zene and the other mothers had all tested negative for HIV and hepatitis.
Mrs Yates said she had feared for the health of her daughter, who is now seven months old.
"We were devastated at the thought of what diseases she could have been given. It would have been a nightmare," she said.
The spokesman for Lewisham Hospital said disciplinary action had been taken. "We have apologised to Mr and Mrs Yates, and made improvements to how we store and manage breast milk in the neonatal intensive care unit to reduce the risk of this happening again.
"This includes making sure that all bottles of frozen breast milk which are being taken home are individually checked by two nurses to ensure that they are for the named baby.
"Disciplinary action has also been taken against the member of staff involved in incorrect milk being given to Mr and Mrs Yates' daughter. They have been put on a period of supervised practice," he said.