Figures showing that hospitals are repeatedly failing to attract suitable applicants for the posts, leaving some positions lying vacant for two years, are said to be threatening the future of children's wards.
MSPs urged Health Secretary Alex Neil to do more to ensure staff are recruited after details were revealed in The Herald.
Labour's shadow health spokesman Jackie Baillie said: "While Alex Neil sits back and does nothing, services are under threat and the recruitment crisis grows. While the SNP fail to listen to more independent voices saying that our NHS is in crisis, the future of our children's hospitals are far from clear.
"With the NHS budget being cut, 2500 fewer nurses and midwives, fewer beds, health boards with budget deficits, record complaints, treatment targets missed and now too few doctors to treat children; we can't trust the SNP with our NHS."
The European Working Time Directive, tightened immigration policies on recruiting staff from outside the EU, and more female doctors taking maternity leave or part-time hours, have been blamed.
Last year, St John's Hospital in Livingston was shut for three weeks due to a short-term staffing crisis.
Scottish Liberal Democrat health spokesman Jim Hume MSP added: "It is clear lessons have not been learnt from the staffing shortage at St John's.
"It is simply unacceptable to have consultants working well beyond the end of their shifts, vacancies going unfilled for two years and hospitals in some cases operating with less than half the paediatric staff they need. Parents must have confidence that wards are operating at world-class levels instead of teetering on the brink of closure."
A Scottish Government spokesman said: "In preparing their workforce plans, [health] boards are required to consider relevant local issues and demographic changes and assess the resultant demands and implications for service delivery."