West Coast expectant mothers have been warned the region has no on-site specialist obstetric and gynaecology cover for two days and they may have to give birth in Christchurch.
One specialist took ill late yesterday and another is on leave.
The West Coast District Health Board could not obtain any locum cover until 5pm tomorrow, said general manager Hecta Williams.
In the meantime, Grey Base Hospital and Buller Health would continue to operate as primary birthing units.
Two more locums were due at the start of next week. No further gaps were anticipated this month.
Two West Coast women were due to give birth over the next week and three the following week, Ms Williams said.
Decisions on whether expectant mothers might need to relocate to Christchurch would be made by the women, in consultation with their lead maternity carers and Christchurch Women's Hospital.
Women assessed as normal risk could choose to deliver on the Coast or travel to Christchurch.
Lead maternity carers would have direct access to advice and support from Christchurch Women's Hospital.
The experienced team of midwives at Grey Hospital's McBrearty Ward, and the hospital's emergency department, had managed similar events previously.
Transport services have been notified additional patient transfers might be required, Ms Williams said.