The hospital-building programme, promised by Mr Johnson as prime minister, has already been beset by delays.
It originally included 40 hospitals but others were added over time.
The projects include complete new builds as well as major refurbishments or alterations.
Shortly after coming to power, Labour said it would be looking at the programme.
But it had not set out which projects would be at risk.
The review is being coordinated by the Treasury, Department of Health and Social Care and NHS England.
It is expected to be completed over the next month, in time for the Budget at the end of October.
The projects to be reviewed are at:
Cambridge Cancer Research Hospital
Charing Cross and Hammersmith Hospitals (London)
Derriford Hospital (Plymouth)
Eastbourne District General Hospital (Sussex)
Hampshire Hospitals
Hillingdon Hospital (London)
Kettering General Hospital (Northants)
Leeds General Infirmary
Leicester General Hospital
Milton Keynes University Hospital (Bucks)
Musgrove Park Hospital (Somerset)
North Devon District Hospital
North Manchester General Hospital
Princess Alexandra Hospital (London)
Nottingham City Hospital
Royal Berkshire Hospital
Royal Lancaster Infirmary
Royal Preston Hospital
Shotley Bridge Community Hospital (Durham)
Sutton Specialist Emergency Care Hospital (London)
St Mary’s Hospital (London)
Torbay Hospital (Devon)
Watford General Hospital
Whipps Cross Hospital (London)
Women and Children’s Hospital (Cornwall)
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