South London Healthcare NHS Trust has admitted to poor data-handling practices that led to the temporary loss of data on 600 maternity patients and 30 children after two unencrypted USB sticks containing the sensitive data were misplaced.
The Trust admitted to the losses in an undertaking signed with the Information Commissioner's Office (ICO).
It is the latest in a series of data handling blunders by NHS bodies.
In the first incident, an employee downloaded the data related to around 600 maternity patients to an unencrypted device in order to carry out some work at home.
In the second incident the details of 30 children were put at risk for similar reasons.
Both devices were subsequently recovered and the ICO said it thought it unlikely the data had been compromised, but nevertheless it forced the organisation's chief executive to sign an undertaking promising improved data handling measures would be implemented.
Details of when the incidents took place were not disclosed in the undertaking.
While the organisation avoided a financial penalty, public sector bodies, including those within the NHS, have borne the brunt of the ICO's recent fines, with councils particularly hit.
Lost USB sticks are frequently the cause of embarrassing data breaches too, with the UK's nuclear safety watchdog admitting in February that an employee lost a USB stick containing information on tests carried out at a facility in Hartlepool.
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