Medical unions say any smaller increase in spending in the Budget could result in district health boards taking abrupt measures to save money.
Unions estimate the increased spend in the health budget could be $350 million less than last year's.
The unions predict the additional health spend could be as low as $400 million, compared with a $750 million rise in 2009.
The Association of Salaried Medical Specialists says that could put pressure on DHBs to make quick decisions about spending, which can be extremely disruptive.
The Nurses Organisation says it can quickly become fear-driven cost-cutting, where innovation and motivation go out the window.
Chief executive Geoff Annals says the Government's challenge is to ensure there are still incentives for DHBs to try to find new ways to provide services while they face financial constraints.