A baby was tested for HIV after she was twice given breast milk from strangers at a south-east London hospital.
Zene Yates, born eight weeks early, was in the neonatal ward in Lewisham Hospital when she was fed the wrong milk through a tube.
When Zene was discharged, a bottle of milk from a stranger was handed to the family - before her mother spotted the mix up.
HIV and hepatitis tests on the child proved negative.
A spokesman for the hospital said: "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."