Stress is being blamed for a high turnover of midwifery jobs and trouble filling vacancies in the South West.
The Royal College of Midwives (RCM) is concerned at the number leaving the profession, with more than 3% of posts unfilled - about 30 jobs.
It said while other parts of the country had reduced the problem, it was getting worse in Devon and Cornwall.
The heavy workload is said to be another reason maternity units have problems replacing midwives who leave.
The RCM is asking for its figures to be taken into account as part of pay deliberations for midwives.