Many NHS maternity units must close so that women having babies can receive better care in large facilities with consultants available around the clock, according to the leader of UK doctors specialising in childbirth.

As many as one in three hospital obstetric units in cities should go as part of a drive to centralise childbirth, Dr Tony Falconer, the president of the Royal College of Obstetricians and Gynaecologists, told the Observer.

While women will have concerns about having to travel farther to give birth, larger numbers of experienced consultants on duty in centralised units would provide higher levels of care at all times, he said. That was necessary because rising maternal obesity and growing numbers of older mothers had made childbirth more complex, and the NHS had too few consultants to guarantee high-quality care for all women, he said.

"One has to embrace the concept of fewer consultant-based units, which provide greater intensity of care. There are quite a few small units and their viability, I guess, you have to question," said Falconer. He urged the NHS to undertake significant rationalisation that would create fewer units handling 5,000 to 6,000 births a year.

He added that an expansion of home births and midwife-led birthing units based at or near hospitals would help reduce the 94% of births that currently occur in hospitals and also lessen the need for the NHS to retain as many obstetric units as it currently had.

Some urban areas such as London had too many obstetric units, he said. "Above the politics of it, the big conurbations are the places that fit more easily with reconfiguration.". The NHS should follow the example of Manchester, where four hospitals lost obstetric units after a review in 2006, in a controversial process that saw then ministers such as Hazel Blears argue against the loss of vital local facilities.

"That [Manchester] seems pragmatically a sensible direction to go [in]. If Manchester is typical, you've got a situation where they made a change from 12 to eight. If that's typical, I have no reason to suspect [it] wouldn't be the same in other huge conurbations," he said.

"Pragmatically when you've got a desire to improve the quality for the more complex cases, a desire to give 24-hour cover, so they get the same quality of [doctors'] decisions whatever the time of day or night, and the workforce issue, there is no other easy solution," he added. Health policy experts argue that London, which has 30 obstetric units and nine midwife-led units in its 32 boroughs, urgently needs major reconfiguration.

Shutting units would cause an outcry, Falconer recognised. "The conflict, the downside of it all, is that from a woman's point of view there's an expectation that your local hospital will provide all core services, including having a baby. The trouble is that people tell me that, 'if you shut our maternity unit here, and I have to go four miles down the road, it will take me an hour to get there'. Presumably there are ways you can get round the transport issues," he said, rejecting such concerns.

David Edwards, an NHS primary care trust board member in Manchester who helped plan the city's centralisation of childbirth services, said: "It was very highly charged. To argue for shutting maternity units is very difficult. People fought it all the way, including local politicians, against the advice of doctors. But if it's better and safer to go somewhere that isn't your local hospital that's on your doorstep, so be it. Maternity units which aren't providing the best possible care, perhaps because they don't have enough staff, should not be championed; instead they should be shut, if necessary."

The leader of Britain's midwives supported Falconer and warned that many smaller units were likely to shut. "We do need to rationalise because, in future, smaller obstetric units won't be affordable if they are too small. For units delivering 2,500 to 3,500 babies a year, their future is a bit gloomy. Units of that size are going to struggle to survive. It's going to be very hard to justify them, unless there's a justification based on geography," said Professor Cathy Warwick, the general secretary of the Royal College of Midwives.

But both Warwick and the parents' charity NCT also raised fears that larger units could become "baby factories". Mary Newburn, the NCT's head of research and information, said the superiority of larger units over smaller ones was unproven and many women preferred smaller units, run by either doctors or midwives.

"We are concerned that very large hospital units can seem like baby factories to parents: impersonal and preoccupied with pushing mothers and babies through the system, that people are processed like components in a factory, and that some don't get personalised care. There's a sense that a woman is a number in such places."

Some women, especially more vulnerable mothers, can "fall between the cracks", she added.

The future of hospital services is back on the political agenda. In 2007 then opposition leader David Cameron promised a "bare knuckle fight" to safeguard district general hospitals and in the 2010 election campaign the Conservatives backed a "moratorium" on planned closures of hospital units.

But the financial squeeze in the NHS, money problems at some trusts, concern about quality of care and a drive to deliver more care closer to patients' homes have combined to throw up a series of local rows over proposed reorganisation in different parts of England.

Andrew Lansley, the health secretary, recently admitted for the first time that his controversial overhaul of the NHS in England could lead to some hospital units being closed with a resultant loss of beds, but insisted that changes would produce better services.

William Hague, the foreign secretary, has backed a campaign to stop maternity and paediatric services being downgraded at the Friarage hospital in Northallerton, North Yorkshire. If that happens some parents would face a round trip of as much as 100 miles from their homes to receive care instead in Middlesbrough.

Health minister Paul Burstow, the Liberal Democrat MP for Sutton and Cheam, is fighting plans to shut the A&E and maternity units at the St Helier hospital in his constituency. Burstow, whose majority is just 1,608, says proposals flowing from a local NHS review "lack reality" and that patients affected will have to spend more time getting to alternative hospitals than the six minutes claimed by the NHS south-west London review team.The Department of Health said that it would support consolidating services if it offered clinical benefits and patient choice. "Local healthcare organisations, doctors, nurses and other health professionals, with their knowledge of the patients they serve, are best placed to decide what services they need for patients in their area," a spokesman said.

• This article was amended on 19 July 2012 to correct the name of Friarage hospital, Northallerton.