About a dozen Hawke's Bay Hospital midwives, who are members of the Midwifery Employee Representation and Advisory Service union (MERAS), will be taking part in strike action on Wednesday.
The eight-hour strike will take place from 11am until 7pm, after pay equity negotiations failed.
It does not affect Lead Maternity Carers (LMCs), chief nursing and midwifery officer for Hawke's Bay Hospital, Chris McKenna said.
She said women preparing for childbirth should not delay seeking care and should come to the hospital as normal.
"If you go into labour during the strike, follow your normal birth plan and let your Lead Maternity Carer (LMC) know as you will have already planned."