"Family Planning is a public health organisation providing incredibly valuable work for our community. But it is simply unsustainable and unfair for our members to be paid less than the going rate for their work."
Members rejected the latest pay offer because they said it failed to address longstanding wage inequity.
FPA nurses were paid at least 6 per cent less than a comparable role within the District Health Boards, Wilson said.
Nurse practitioners could gain between 13 and 27 per cent more pay with a career move to the DHB.
Half of wages for medical receptionist and administration roles were below the living wage, Wilson said.
FPA had been underfunded for at least a decade, Wilson said, which was why it could not offer higher wages.
While the NZNO acknowledged the FPA offered higher increases than in previous years, staff should not have to make up the funding shortfall by working for lower wages, Wilson said.
"It is time the funding provided to the FPA matched the value it gives to the wellbeing of our community."
There would be a mediation session before the strike date, and Wilson said they remained hopeful funding could be found to settle the dispute.
"Our members don't want to strike and this has never occurred previously.
"They are passionate about the fantastic service they provide and want to remain and also be able to attract staff to the service.
"They need wage rates that recognise the true value of their work in comparison to their peers and further a living wage for all staff.
"However, when community health appears to be valued at a lower rate than hospital care, they know the community is relying on them to improve it."
The strike will take place from 7am on December 13 to 7am December 14.
