The result of the ballot, the first in the RCM's history, was announced yesterday. Overall 82% of members agreed to strike. Altogether 10,536 votes were cast, equating to a turnout of 49% of eligible members.
Midwives will join members of Unite and Unison, who voted in favour of a strike last week, in a day of action on 13 October. Subsequently there will be four days in which members of all three unions will refuse to work any unpaid overtime.
RCM chief executive Cathy Warwick said the result of the vote "could not send a clearer signal" about the discontent over continued pay restraint.
"Our members have suffered three years of pay restraint and face the prospect that their pay in 2016 will only be 1% higher than it was in 2010," she said. "The recommendations from all public sector pay review bodies have been followed except those for health workers. This is not acceptable."
Warwick also reassured expectant mothers that midwives would continue to look after them and that "they will be safe". The disruption to services will occur in non-urgent pre-natal and post-natal care.
NHS Employers director of employment relations and reward Gill Bellord called the strike "regrettable" but welcomed the assurances around patient safety.
"Employers will be concerned that this industrial action could worry pregnant women," she said. "However we welcome indications from the RCM that its members will continue to provide cover on maternity wards and work with local employers to ensure services can be maintained safely on the day of the proposed action.”
Maude attacks 'out-dated' ballot rules
Conservative minister for the cabinet office Francis Maude has reiterated a pledge to stop unions calling strikes if they don't have the support of more than half their members.
Maude made the announcement in his speech to the Conservative party conference. He vowed to end strikes where the ballot had a turnout of less than 50%.
"It just isn't right that an unrepresentative trade union baron should be able to close schools or bring the Tube to a stand-still, when they can't even persuade half of their own members to vote," he said.
The government's review into union practices suffered a setback last month when judge Bruce Carr QC, charged with investigating union activity, refused to give legal advice due to what he called a "politicised environment".