Care for sick and premature babies is at "breaking point" because of a shortage of nurses, a charity has said.
Demand for care in neonatal units has increased in Wales
A report by Bliss said demand for care in neonatal units in Wales had jumped by 13% in 2006, while the number of specialist nurses rose only by 2%.
It also said overcrowding meant some new admissions were turned away.
The Welsh Assembly Government said Bliss had been advising it on neo-natal facilities and developing specialist services for children and young people.
However, a spokesperson said: "We cannot comment on reports we haven't had an opportunity to study in detail."
The charity for premature babies said no unit in Wales currently met the recommended nursing levels.
It said more than 100 specialist nurses were needed - increasing the workforce by 27% - to meet recommended minimum standards in Wales.
The study said services were being "stretched to breaking point" and said the units had to close their doors for an average of 24 days in a six-month period.
It said that this meant mothers and babies sometimes had to travel long distances to access the care they need.
Louise Downie, from St Mellons, in Cardiff, was moved from the University Hospital of Wales after she went into labour at 34 weeks in December 2006.
Louise Downie went into labour when she was 34 weeks pregnant
Ms Downie said there was not a neonatal cot available for her and she was taken to Nevill Hall Hospital in Abergavenny within hours.
"You would think, living on the doorstep of the University Hospital of Wales, you would get access to the best health care - but I had to travel 30 miles away," she said.
After seven days at Nevill Hall, her son Sammy was transferred back to the University Hospital and was there for five days before being discharged.
Ms Downie said the whole process and her experience had made her wary of a second pregnancy.
The report showed demand for care in neonatal units in Wales had jumped by 13% in 2006, while the number of specialist nurses rose only by 2%.
Tina Donnelly, director of the Royal College of Nursing (RCN) Wales, said she was concerned with the findings.
"It is essential that nursing numbers and skills match and are available, when required, to meet the needs of patients," she added.
The RCN believes NHS health organisations in Wales should have statuary responsibility to provide the right number of registered nurses for patient care.
"Without this in place we will see an impact on service provision and the level of patient care, as is the case with the neo-natal units in Wales," Ms Donnelly added.
The report by Bliss also said there was no dedicated transport system in place in Wales to transfer babies safely between units.
Based on replies from 11 of Wales' 13 units, the charity also surveyed parents of sick or premature babies on their experience of neonatal care.
Bliss chief executive Andy Cole told BBC Radio Wales he hoped the assembly government and Health Commission Wales, which in 2005 began a review of neonatal services, would develop a "really strong strategic plan" for the speciality.
He said: "These aren't nurses that grow on trees, they require training. They will require a couple of years to come on line.
"We need to see there is some investment coming in now to make sure those nurses are recruited and retained, they are valued within the NHS and to make sure we are dealing with the issue now."