A shortage of midwives is putting newborn babies' lives at risk, a report published in the British Medical Journal has warned.

The study found that the risk of complications during childbirth is increasing due to a lack of qualified staff.

Researchers examined services at seven hospitals in North West England. All had staff shortages, a problem which contributed to 15 near-misses and one adverse event during the study.

Although the authors estimated that there were 2.5 to five near-misses per day on average in each of the units, a number of incidents went unreported.

In six of the seven units, midwives were spending considerable amounts of time on clerical duties rather than working with patients.

"The system cannot operate safely and effectively when the number of midwives is inadequate, midwives are poorly deployed and they are unable to engage in opportunities for training and updating," said the report.

"We observed many accidents waiting to happen."

The Department of Health defended the government's record.

"The number of midwives entering and returning to the NHS is increasing, but we are committed to improving the recruitment, retention and training of midwives working in the NHS," said a spokeswoman.

"In 2002, there were 870 more midwives employed in the NHS than there were in 1997, and between 1999 and 2003, 1,200 formermidwives had returned to work in the NHS.

"There are also more midwives entering training - since 1996-97 the number of midwives entering training each year has gone up by 28 per cent.

"We recognise the importance of training continuing after registration, which is why we have put in an extra £96 million for programmes to continue nurses' professional development. A Nursing Task Group has also been established to examine the education and development of nurses and midwives after registration.

"The government has provided £100 million over two years to modernise and upgrade over 200 maternity units in England.

"The maternity module of the Children's National Service Framework will look at how to make maternity services more flexible, accessible and appropriate to meet the particular needs of the woman and her baby."

But shadow health secretary Dr Liam Fox blamed the impact of targets for the staff shortages. "Midwifery under Labour, like nursing, has become a demoralised profession," he said.

"Above all, staff feel less and less able to do the work they were trained to do in the way they want to do it - because they are forced to spend more and more of their time pursuing government targets.

"So it's little wonder that there is such a shortage of midwives."

The Liberal Democrats described the findings as "alarming."

"Midwife vacancies create a vicious circle of tiredness for nurses, extra work, poor morale and even more vacancies," said health spokesman Dr Evan Harris.

"The shortage of midwives puts existing staff under greater pressure and increases the chances of a mistake being made or something being overlooked.

"Mums to be will be the ones who lose out from a decline. The quality of care they get and their confidence in the system will suffer."

The Royal College of Midwives said that pay would have to be addressed to encourage more people to enter the profession.

Responding to the report, general secretary Dame Karlene Davis argued that changes in working practices had increased the stresses placed on midwives.

"There are currently 5,000 less midwives practising than there were 10 years ago," she said. "Despite the fact that people are training and entering the profession in record numbers it simply doesn't compensate for the number of midwives leaving."

"The high Caesarean section rate is a major cause of increasing midwives workloads and the rates tend to come down when midwives are able to spend time with women throughout their labour."