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.