Concern over the way premature and sick babies are cared for is deepening, says the charity Bliss.
The charity Bliss said the shortages are costing lives
A survey of UK neonatal units revealed 90% of specialist intensive care units had to close their doors to new admissions last year.
Babies were also being regularly transferred between hospitals because of staffing and cot shortages.
Bliss said lives were being lost, but the government, while accepting problems, denied there was a crisis.
The research, carried out by the National Perinatal and Epidemiology Unit (NPEU) at Oxford University, for Bliss, surveyed 64% of all neonatal units in the UK; every neonatal network (a cluster of hospitals in a region that provide a wider coverage of neonatal care) in England, and 216 parents.
It revealed the situation in neonatal care was getting worse compared with a similar report carried out last year.
The survey found 78% of neonatal units had to turn babies away, mainly because of a shortage of nurses and cots, a rise of 8% on the figure for 2005.
And it discovered 90% of intensive care units - the departments that provide the highest level of care to the sickest babies - had to close their doors on new arrivals.
That represented an increase from 80% in 2005.
The survey also showed the nurse-to-baby ratio was well below the optimum required in intensive care units.
Only 3% of trusts said they managed to operate at the recommended level of one nurse to each baby.
Rob Williams, chief executive of Bliss, said: "Presently, a baby in intensive care receives a lower ratio of care than an adult in an intensive care unit.
"This is not an academic issue; it is a patient safety issue. We are convinced if we had the right level of nurses in intensive care, survival rates would improve."
The charity also said three babies a day were being transferred between hospitals, some having to travel hundreds of miles. The vast majority of the neonatal networks surveyed said these transfers were caused by staff shortages.
Mr Williams said transfers should be a rare event, but the current figures were two to three times higher than those recommended.
He said: "The UK has one of the worst infant mortality rates in western Europe.
"Most of that mortality happens in the first month of life, to premature babies. But we are not providing the basic level of intensive care for babies."
He said the Department of Health had not taken a lead in saying that babies needed the same levels of intensive care as adults, and had not committed to the one baby to one nurse ratio.
He added that very little of the extra £70m committed to neonatal care had been spent on improving care.
In the UK, one in eight babies needs to be looked after in a neonatal unit at some point, and about 18,000 babies a year will require the highest level of intensive care.
This is mainly due to social trends, such as women giving birth later in life, IVF pregnancies boosting the number multiple births and more teenage mothers, but it is also consequence of the fact that medical advances mean increasing numbers of premature babies survive.
Health Minister Ivan Lewis denied that there was a "national crisis" but acknowledged there were challenges.
He said: "There are problems that have to be tackled with staff and other issues."
But he said the government had taken action to improve access to cots and insisted infant mortality rates were at their lowest ever.
"In many cases there are cots lying empty in some areas whilst in others the ward or the facility is full.
"Getting that supply and demand right has to be sorted out at a local level which is why we've developed these local clinical networks.
"I will be having a close look at what is happening on the ground because it is very, very important - there is nothing more important actually than we look after babies who are at risk at this stage in their lives."