The health board employs 44 midwives and 765 nurses, many of whom are union members. Anyone who will be affected by alterations to planned hospital care is being contacted.
Lakes DHB chief executive Nick Saville-Wood said the DHB will be able to maintain only minimal services during the strike. He said patient safety is the number one consideration in planning for the upcoming industrial action.
Tauranga and Whakatāne hospitals will only be open for emergency, essential services, and urgent medical care on Thursday.
Most non-essential services and elective surgery is being postponed.
In a media statement, the Bay of Plenty District Health Board said the effect of removing a large percentage of the nursing and midwifery workforce, even for a short time, was "hard to overstate".
Maternity care for women and their pēpi will be as normal.
Planned caesareans will be rescheduled while urgent caesareans will not be delayed.