New Zealand's junior doctors will take the very serious step of going on strike tomorrow for 48 hours. So what's really behind the strike action and where could it lead?

Up to 3000 junior doctors across the country are expected to begin strike action as they call for changes to rostering.

The union representing them wants the maximum number of days junior doctors work in a row cut from 12 to 10, and the number of night shifts worked reduced from seven to four.

Many of New Zealand's junior doctors have complained that they're often worn out from working long hours, and say the safety of their patients is at risk.

National Secretary for the New Zealand Resident Doctors' Association (NZRDA) Dr Deborah Powell, told Newshub: "I'm surprised it's got to a strike, this [current rostering] is a significant health and safety issue, I honestly didn't think it would get to this point."

"After four years of trying to get this sorted we simply don't trust the DHBs' commitment to the issue. We want it confirmed in a contract so that it is legally binding," she added.

The strike will be disruptive to District Health Boards (DHBs), with outpatient appointments and elective surgeries having to be postponed.

DHBs will have to pay them $568 an hour for any extra hours worked.

The country's junior doctors graduate with a student loan that in most cases is up to $100,000.

They then enter the workforce and are expected to work 60 hours a week, but many end up working 72 hours a week and 12 days in a row without a break.

Their annual salary varies depending on which region they're working in, but on average it is at least $100,000 a year.

Junior doctors receive six weeks' annual leave a year, and also six weeks a year for study leave to help further their careers.

Spokesperson for the DHBs Julie Patterson told Newshub: "We want to get the health and safety issues that the junior doctors' union has raised with its members sorted."

But she added: "We do have to have the union make some movement in order to fix those health and safety issues that they are reporting."

Three years ago there was a surplus of junior doctors coming out of New Zealand's medical schools, and at least half of all graduates headed overseas chasing bigger wages. Most headed to Australia.

This pattern of young Kiwi doctors heading overseas has continued.

Almost half of the country's junior doctors are actually immigrants, and that's led to New Zealand having the highest dependency on international medical graduates in the OECD.

If the current situation continues in New Zealand, then DHBs could face a similar situation to that of Britain's National Health Service (NHS).

In the UK there has been a bitter two-year dispute between the government and the junior doctors' union culminating in a prolonged strike.

The NHS wanted its junior doctors to work more on weekends and offered new contracts with no significant pay rises. These proved massively unpopular resulting in the first ever all-out strikes in the history of the NHS.

The morale of doctors working in the NHS is said to be generally low, and many have headed overseas.

The DHBs are looking to resolve the issue but it may take some time. The NZRDA say all it's being offered by the DHBs is a commitment to reduce junior doctors' work hours, instead of a new contract.

Dr Powell told Newshub the DHBs are taking too long to act: "The DHBs want two years to implement this - we think that's unnecessarily long."

She added: "We also want to sort out recuperation time after these long stretches of work. We need to make sure doctors have meaningful rest and recuperation before they come back to work, and the DHBs haven't come to the party on that one yet."

So this initial strike could lead to others and further disruption, if the concerns of junior doctors aren't acted upon.

Newshub.