An inquiry into maternal deaths will be launched today amid increasing fears that cuts to maternity services are putting the lives of mothers and their babies at risk.

The review will call on obstetricians, midwives and birthing charities to explain what is going wrong after a run of deaths in labour wards. It is to be conducted by the King's Fund, a leading health charity.

Last summer an inquiry by the Healthcare Commission into the deaths of 10 new mothers at Northwick Park hospital, north-west London, blamed a lack of staff and breakdown in communications. The commission has also launched a nationwide investigation into safety.

It comes amid worries about recruitment freezes in maternity wards, the closure of several birthing units and the threat of more closures after David Nicholson, the NHS chief executive, said maternity services should be reorganised into fewer, more comprehensive centres to save money.

Niall Dickson, chief executive of the King's Fund, said: "There is growing concern about the safety of maternity services and sufficient evidence to suggest that all is not well.

"We know there have been dramatic improvements in maternal and child health over the past 50 years. But there is now evidence to suggest outcomes for some groups are deteriorating."

Lady Onora O'Neill, president of the British Academy and the inquiry's chair, said that it would focus on why women from poorer backgrounds were more at risk. "This review should give us the knowledge base we need to tackle these problems effectively, and ensure all maternity services in this country meet high standards of care."

Separately, the Royal College of Obstetricians and Gynaecologists and Royal College of Midwives are due to publish the first revision in a decade of the seminal document Towards Safer Childbirth, outlining how maternity services should work. The Guardian understands that they will call for more senior staff on wards increasingly run by junior doctors.

The recommendations are likely to be controversial as hospitals struggle with deficits. If hospitals were compelled to employ a few more consultants at the cost of midwives, the quality of midwifery services could suffer. Childbirth charities also suggest it could threaten the government's promise to give mothers more choice in childbirth before 2009.

Mary Newburn, head of policy at the National Childbirth Trust, said: "The Northwick Park report was a wake-up call for everybody. In London there are big increases in women having babies so services don't have the staff to provide good quality care - we don't know what effect that has on safety. There are a lot more near-misses than tragedies but that's not good enough."

A spokeswoman for the Department for Health said it was committed to increasing choice for women by 2009. She added: "We want to ensure that women have as much choice as possible about the type of care they receive during their pregnancy, throughout labour and birth and postnatally while minimising any known risk to either themselves or their baby."

The most recent research on maternal deaths, for the years 2000-02, said 391 women died while giving birth or soon after - a little over 13 per 100,000 new mothers and a slight increase on previous years.