Women who expect to give birth on the West Coast over the next two days will have to travel to Christchurch for specialist care if they need it.
The West Coast District Health Board says that because of an unexpected illness no specialist obstetric and gynaecological care is available until Thursday evening.
It says another specialist is away on leave and it has been unable to get temporary cover.
The manager of midwifery services on the West Coast, Jude Bruce, says five women are potentially due in the next two weeks, and two were transferred to Christchurch on Wednesday as a precaution.
Ms Bruce says they do have plans in place in case emergency care is needed for any of the women remaining on the West Coast.
She says they could fly a specialist in from Christchurch to perform a caesarean, or fly the pregnant women to Christchurch, with the response depending on the woman's particular circumstances.