Many maternity units in England are failing to provide top quality care, an independent review suggests.
The Healthcare Commission found huge variation in quality of care across England with women in London receiving the worst service.
The report also highlighted problems with staffing and inadequate screening checks in some trusts.
Health Secretary Alan Johnson has announced extra funding for maternity services over the next three years.
It is the first time such a wide-ranging review of maternity services has been carried out.
'Least well performing'
Just over a quarter of the 148 trusts assessed were classed as "best performing" on 25 factors which included screening tests, ante-natal care and midwife support.
But 21% of trusts fell into the "least well performing" category.
In London, antenatal and postnatal care tended to be consistently poorer, with women not having as many checks as recommended, and inconsistent quality of care around the time of birth.
In contrast, in the North, 33 out of 44 trusts were ranked as "better performing" or "best performing".
The review, which also took into account a survey of 26,000 mothers, was launched in response to concerns about maternity services.
Data collected from trusts showed that 40% of ultrasound scans carried out fail to fully check for abnormalities in unborn babies.
A quarter of trusts reported breast feeding initiation rates of 58% or less, while the highest performing trusts reported rates of 78% or more.
A third of hospitals did not have the recommended level of attendance by consultants.
And nine trusts had only 26 midwives per 1,000 deliveries compared with an average of 31 midwives per 1000 deliveries - experts recommend 36 per 1,000 to achieve one-to-one care.
BEST MATERNITY CARE
Stockport NHS Foundation Trust
Gateshead Health NHS Foundation Trust
North Cumbria Acute Hospitals NHS Trust
Northern Devon Healthcare NHS Trust
Northumbria Health Care NHS Foundation Trust
County Durham and Darlington Acute Hospitals NHS Trust
Royal Cornwall Hospitals NHS Trust
Salford Royal NHS Foundation Trust
Hull and East Yorkshire Hospitals NHS Trust
Wirral Hospital NHS Trust
Anna Walker, the Commission's chief executive, said care in the worst performing trusts was not unsafe and they would take immediate action if it was.
She added that there were real concerns about maternity care in London and trusts need to "rise to the challenges" faced in the capital.
Mary Newburn, of the National Childbirth Trust, said: "Women can be emotionally traumatised by a lack of support when they are in labour or coping with a new baby, and can be left needing months of physical or psychological recovery with long-term scars."
Health Secretary Alan Johnson announced extra funding for maternity services that will increase over the next three years to reach an additional £122m annually.
He said the funds would help ensure women get a choice over where to give birth, improve flexibility of maternity services' opening hours and increase the number of midwives and support staff.
"I want to see the NHS delivering a gold standard of maternity services for women in every part of the country," he said.
The Royal College of Midwives said any extra funding was welcome but that the government was "playing catch-up".
WORST MATERNITY CARE
St Georges Healthcare NHS Trust
Barts and The London NHS Trust
Luton and Dunstable Hospital NHS Foundation Trust
Bromley Hospitals NHS Trust
Mayday Healthcare NHS Trust
Homerton University Hospital NHS Foundation Trust
Chelsea and Westminster Hospital NHS Foundation Trust
Barking, Havering and Redbridge Hospitals NHS Trust
Newham University Hospital NHS Trust
West Hertfordshire Hospitals NHS Trust
They estimate 5,000 extra midwives are needed to cope with rising birth rates.
RCM spokesperson, Jon Skewes said: "We need to put this in context - last year there was a cut in budget of £55m, so some of this looks like it's restoring money."
Maggie Blott, a consultant obstetrician and spokesperson for the Royal College Obstetricians and Gynaecologists, stressed that the UK had some of the safest maternity services in the world.
"It is very important to keep that perspective so that women who are pregnant do not get concerned about the services that are provided for them," she said.