Staffing shortages at baby units across Wales
More than 80 new nurses are needed to ensure staffing levels at Wales' 13 neonatal units meet recommended requirements, a report has warned.
A deficit of nurses is "substantial and present in every health board and unit", the Assembly's Children and Young People's Committee said.
The AMs said despite recommendations made two years ago units still lacked resources and relied on staff goodwill.
The Welsh government said more needs to be done.
Around 4,000 sick and premature babies are admitted to Wales' 13 units annually.
Recommended staffing ratios on the number of nurses per baby are not being met, the committee heard.
An assessment found the equivalent of almost 83 full-time nurses were needed to make up the shortfall.
It comes despite a previous health committee inquiry in July 2010 calling for urgent measures to address the problem.
Although there have been improvements, progress appears to be slow, according to the latest report.
It added: "A number of witnesses told us about the intense pressure and stress they work under, and we believe there is an over-reliance on the goodwill and dedication of staff to keep under-resourced units running."
It said AMs were "alarmed" to hear that a number of health boards were relying on paediatricians instead of dedicated neonatologists.
The report lists difficulties with the availability of cots and the support available to parents, which varies between units.
It said health boards should draw up plans on how they will cope with a shortage of nurses.
It welcomes the creation of a 12-hour neonatal transport service, saying the Welsh government should go further and look at the cost of providing round-the-clock transport for families.
Sybil Barr, a neonatal consultant in Cardiff, said: "There are some days when we skirt close to the wind.
"We have to work at a percentage occupancy that is significantly higher than what's agreed as a safe level and when that happens day after day after day that is a dangerous situation.
"We do the best that we can and we are getting away with it, and I hope that we continue to do that.
"However, it's not an ideal situation and results such as this inquiry should hopefully propel us in the direction where we get more neonatal nurses so that we can safely staff the cots that we do have and hopefully staff the further cots that we need."
Andy Coles, chief executive of the neonatal charity Bliss, said: "In recent years there has been some significant progress in improving neonatal services, however there still much more to do to ensure the very best care is delivered to these vulnerable babies and their families in Wales."
The report highlighted "serious concerns" in relation to the situation in north Wales.
In written evidence Bliss said that the provision of ongoing intensive care to babies in Ysbyty Glan Clwyd, Bodelwyddan, Denbighshire, and Wrexham Maelor Hospital, was not "even approaching compliance" with the All Wales Neonatal Standards on medical staffing.
In its response, the Betsi Cadwaladr University Health Board, which manages the hospitals, said it was trying to achieve the standard which recommends eight consultant neonatologists.
A Welsh government spokesman said it acknowledges further improvements are needed to provide consistent high-quality care.
"The committee's inquiry highlights issues already identified in the government's plan, Together for Health, such as recruitment and training of certain medical staff and some specialist services being spread too thinly," he said.
"Together for Health puts the case for modernising services. Creating specialist centres of excellence, alongside more care closer to home, will improve quality of care.
"Local health boards are developing plans to improve their services and meet the aims of Together for Health."