A study in the British Medical Journal suggests a shortage of midwives has increased the risk of women having complications during childbirth.
Ministers want to recruit an extra 10,000 midwives by 2010
BBC News Online examines why so many midwife posts are vacant.
One year ago, the Royal College of Midwives warned of a crisis in the NHS because of a major shortage of qualified midwives.
It declared that vacancy rates were at critical levels and that urgent action was needed to tackle the problem.
In May of this year, the situation had hardly improved.
Again, the royal college called for something to be done.
The government says it is doing all it can to fill vacant posts.
Ministers are committed to recruiting 2,000 extra midwives by 2004 and a total of 10,000 over the next seven years.
However, there are growing fears that this recruitment drive will have little impact.
A record number of midwifes are retiring early and as many as one in 10 students decide the profession is not for them soon after they qualify.
Voting with their feet
Earlier this year, the royal college carried out a survey to find out why midwifes are voting with their feet.
It found that one in three of those leaving were doing so because they were dissatisfied with midwifery.
Another third were leaving because of either family commitments or because they were changing careers.
"It is probably a combination of factors," says Sue Macdonald, a practising midwife, who also works at the royal college's education and research department.
"Many midwives don't feel valued. While some of this has to do with money, it is not the only issue."
The profession appears to be caught in something of a catch-22.
While more and more midwives are leaving the NHS, the vacancies and extra work are encouraging others to leave too.
So what can be done to make them stay?
Agenda for Change, a new pay deal for NHS staff including midwives, is due to come into effect next year.
It promises better pay and streamlined pay structures.
"I think it will make a difference," says Ms Macdonald.
"But I think we really need to make midwives feel valued as practitioners."
In recent years, there has been a move towards setting up small teams of midwives, comprising six or so people.
Together they provide care to a relatively small group of pregnant women in their local area.
This means that they work regularly and closely with these women.
In the past, new mums may have dealt with a different midwife at every turn of their pregnancy.
"The changes have made a difference," says Ms Macdonald.
"Studies have shown that midwives who work like this are much more positive and much more satisfied with their jobs.
"Although further research is needed, I think perhaps we should consider moving towards that model of care for everyone."
Ms Macdonald also believes that improving the lot of newly-qualified midwives could dramatically improve the situation in the NHS.
"I think their could be better remuneration for students. They have a limited bursary and the first year is difficult.
"More money could keep them and show that they are valued."
Getting time off to keep their medical knowledge up-to-date is also an issue for many midwives.
Midwives are expected to do in-service training or continuing professional development.
However, many find it difficult to get the time off work to do this.
"We need to make sure they have the opportunity to attend continuing professional development," says Ms Macdonald.
"It is all about ensuring midwives get satisfaction from the work they are doing."