The head of the Royal College of Midwives has voiced fears for the future of midwifery because of tight budgets, a high birth rate and increasingly complex births.
RCM General Secretary Cathy Warwick was responding to a survey suggesting maternity units are already seeing budget and staffing cuts.
The findings will be discussed at Tuesday's RCM annual conference.
The Department of Health said it was looking at ways to improve recruitment.
The RCM questioned heads of midwifery across the UK. A total of 83 out of 194 responded, a response rate of 43%.
Nearly a third (30%) said they were facing budget cuts, and 33% had been asked to cut staff.
Job cuts predicted
Two-thirds (67%) said they did not have enough staff to cope with demand. Nearly half (47%) said they expected to have to make job cuts over the next year.
Midwives said this was happening while increasingly complex births were making their work more demanding. They said there were growing numbers of obese, teenage and older mothers-to-be who often need extra support.
The number of midwives has been rising more slowly than the number of births in England over the last decade; the birthrate has gone up 19% while midwife numbers have risen 12%.
RCM General Secretary Cathy Warwick said the findings were deeply worrying.
"We are seeing static or falling budgets, yet midwives and maternity services are faced with a continually rising demand," she said. "Whichever way you look at them, the figures are not adding up.
"I have great fears for the future. If maternity services are struggling now, how will they cope when there is less money?
"Over the past few years we were starting to see improvements, and now my real worry is that it could now all come tumbling down."
The survey will be discussed at the RCM annual conference, getting underway in Manchester.
It backs up the findings of the NHS staff survey published earlier this year. That found that the majority of midwives had experienced staff shortages, with over half saying this was affecting patient care.
Health Minister Anne Milton said the government was considering ways of improving midwife recruitment and retention. She said ministers would work with the RCM to make sure midwives were properly resourced and skilled.