Hundreds of thousands of health workers will today go on strike in protest at the Government's decision not to give them a 1% pay rise.
For the first time in history, midwives will join picket lines mounted outside hospitals and ambulance stations across the country.
Several trade unions will be involved in the action, including those representing nurses, paramedics, hospital porters and ambulance crews as well as the Royal College of Midwives (RCM).
The strikes could see around 400,000 refuse to work in England for four hours from 7am, with action planned later in Northern Ireland.
Contingency plans have been worked out, and union members will deal with emergencies.
The Royal College of Midwives will take part in the action for the first time in the organisation's 133-year history.
Cathy Warwick, the college's chief executive, said: "Midwives are caring people who often work long hours of unpaid overtime just to keep our understaffed, under-resourced maternity services running in the midst of a decade-long baby boom.
"They deserve this modest 1% pay rise."
Unions are protesting at the Government's decision not to accept the independent pay review body's recommendation to award a 1% pay rise to all staff.
Instead, ministers took the decision to award a 1% pay rise for those on top of their pay band, which unions say has denied the 1% increase to 60% of NHS workers in England.
In Wales, thousands of NHS workers will vote on whether or not to strike after a similar offer was made.
In Scotland, all staff were granted the recommended 1% pay rise.
No decision has been made in Northern Ireland.
Rob Webster, chief executive of the NHS Confederation, said: "We are working through some of the toughest times in the history of the NHS.
"A pay award for all staff on top of increments would have cost £450m more - the equivalent of 14,000 newly qualified nurses.
"Hard-pressed staff would have been put under greater pressure or may have had to be reduced.
"Restraining pay was a tough decision for politicians to make and I believe they did it on the basis of improving the quality of care and maintaining continuity of services."
NHS bosses say non-emergency appointments will be postponed during the strike and emergencies won't get ignored.
But ambulance service providers say they may be forced to prioritise their care and are bringing in extra staff from the military to fill in the gaps.