The survey by the baby charity Bliss was based on Freedom of Information requests to every special care baby unit in the UK.
Of the 163 units that responded, only 35 (21%) said they had sufficient nursing staff and only 14 of the most specialised level three units can meet minimum standards.
Bliss has estimated that there is a shortage of around 1,700 qualified neonatal nurses across the UK.
It estimated that there are around 6,500 specialist neonatal nurses currently working in the country – and for units to operate at the 70% capacity necessary to cope with peaks in demand, there needs top be at least 9000 neonatal nurses, the report said.
More than half (55%) of units said they had to close to new admissions at some point between 1 April and 1 September 2007.
On average, units closed to new admission for an average of more than two 233ks over a five month period – the equivalent of five weeks over a year.
Seven units had to close for a total of three months over the period – the equivalent of seven months over a year.
Over the period, 491 babies were transferred because of a lack of capacity, equating to around three babies a day.
Furthermore 35% of in-utero transfers and 36% of ex-utero transfers were to units outside their area.
Andy Cole, chief executive of Bliss, said: ‘Professionals are increasingly being stretched to the limit. Staffing shortages are all too apparent on units and the care of our most vulnerable babies is being compromised.’