Four years ago, Stephanie Sher had a decision to make. It was one many women face every year, though this does not lessen the stakes. Pregnant with her first child, Sher needed to decide how best to deliver her baby.

"Childbirth is a very personal thing. It's about weighing up the pros and cons for each individual. There are risks and benefits in whatever you do," she tells me.

Sher, 38, chose an elective caesarean. Not because she was too posh or too scared to push but because she decided it was the safest method. In fact, Sher makes decisions on delivery and surgery every day, and she understands the consequences more than most - she is a consultant obstetrician.

One London study published in the Lancet in 1996 reported that 31% of female obstetricians would personally prefer a caesarean birth. In the US, the figure is almost 50%. Many female surgeons and GPs quietly take this option too - though, as one told me, "to admit as much is still massively un-PC".

In April 2007, the then health secretary, Patricia Hewitt, launched her strategy for the future of maternity care. Maternity Matters trumpeted "choice", promising better access to "normal" deliveries via home births and midwife units. Her plans chimed with recent guidelines from the National Institute for Clinical Excellence (Nice) drawn up to reduce caesareans - currently 23% of all births - by advising obstetricians against granting them without medical justification. The official disapproval of elective C-sections means Sher daren't talk under her real name; Stephanie Sher is a pseudonym.

So while the government promotes "normal" deliveries to the public, its employees are privately planning caesareans. Why do so many obstetricians opt not to push? What do they know that we don't?

It's important to remember that it is the obstetrician's and the surgeon's task to remedy the rarer complications and consequences of childbirth. Unlike midwives, who oversee successful, normal births every day, doctors bear witness to the worst-case scenarios.

Inevitably this difference in experience manifests itself in an ongoing debate on how best to manage childbirth. Midwife groups advocate normal delivery and "natural" births while obstetricians tend to see medical intervention as a benefit rather than a bane. Yesterday, the healthcare commission published a report highlighting several key problems in Britain's maternity services, one of which was an inherent tension between midwives and doctors on maternity wards. Caught up in the middle are the mothers.

Maternity experts across the board believe that a straightforward vaginal delivery is by far the best for both mother and baby. Most women agree: 63% of mothers see childbirth as a natural experience that should not be interfered with unless necessary. In "putting women at the centre of maternity provision", the government's strategy reflects the overwhelming consensus.

Nevertheless, among all the furore that surrounds the issue of childbirth, for Sher and her colleagues, one thing is clear: the government's promotion of delivery "choice" is a promise rarely kept. "There is nothing wrong with hoping for a natural event," Sher says, "and for everything to happen beautifully. But it just isn't like that for a large proportion of women."

Sher's greatest fear was not the pain of spontaneous labour. It was the prospect of emergency intervention, if the birth went wrong. According to the most recent NHS maternity statistics made available (2005-6), just under half (47%) of expectant mothers have a regular, uncomplicated "normal" labour. The rest have interventions ranging from induction, to forceps, to an emergency caesarean. In other words, when a woman tries for a normal birth and the best, safest kind of delivery, she has only a 50% chance of achieving it. For a significant number of others, the birth will be more complex.

With odds like this, it is not illogical to consider alternatives, particularly not if your line of work exposes you to the most extreme of cases. Many obstetricians find the second safest solution is a planned caesarean. The National Caesarean Section Audit (2001) revealed half of obstetricians think this is the safest delivery method for the baby - though not for the mother.

The surgical risks of a planned caesarean include haemorrhage, thrombosis and infection. Scarring on the uterus means the more caesareans you have, the more risky later pregnancies become. But Sher knew she only wanted two children and made the choice that suited her best - both were delivered by C-section. The baby's safety was her primary motive - but not, she adds, the only one. "The other issue was the risk of pelvic floor damage. Again small, but to me, just not worth it."

Vaginal delivery is a major factor in womb prolapse, urinary and faecal incontinence. If the woman's perineum or sphincter is damaged during childbirth, she will not necessarily be affected straight after the birth. But when she hits the menopause and the pelvic floor muscles begin to atrophy, problems can arise.

Michelle Thornton, a colorectal surgeon, sees around 100 women a year suffering from faecal incontinence. "I'm seeing the end result of a traumatic birth," she says. "Very few of my colleagues would opt for a vaginal delivery and, if any of them asked me, then it's an elective C-section."

Some 42% of women show some symptoms of urinary incontinence, 4%-12% of women suffer from faecal incontinence. According to Thornton, "If you have a forceps delivery the chance of having faecal incontinence increases to 40% or 45%. If you have an elective caesarean you shouldn't have any issues."

Not all experts agree that the risks of a surgical birth outweigh the benefit of protecting the pelvic floor. But calibrating clinical percentages is different from witnessing the lives of women with faecal incontinence, says Thornton. "It's definitely altered the way I think about childbirth. The thought of being faecally incontinent - to have a life like my patients - I don't think I'm strong enough."

Thornton feels the stigma attached to incontinence is as bad, if not worse than the physical symptoms. "Most are too embarrassed to go out," says Thornton. "They will not go anywhere unless they know there is going to be a toilet. They can't use public transport; they don't go out for meals . . . Only two of them have managed to keep a job, the rest don't because they think they smell all the time. If they cough or sneeze or laugh they know they are going to leak."

Among her patients, Thornton has half a dozen women in their early 30s. They have "bonding issues with their babies . . . as well as young partners expecting to resume a normal sexual relationship. Two of the couples have split up because of the traumas." She counsels patients both psychologically and physically. "Emotionally it is tough," she says. "Having those patients with you when they get upset is tough." When treatments fail, "it's terrible, because the patient is absolutely gutted". Her patients know a permanent colostomy is the only solution. Imparting this news always makes Thornton anxious. "It's a terrible feeling. It's like giving them a cancer diagnosis."

When it comes to medical matters, we assume that knowledge is a good thing. Looking at the childbirth choices made by some female doctors, we might think their superior professional experience makes them right. But many admit their exposure to complications inevitably taints their personal choices. Is it really better to know what they know? Perhaps it's not that most women don't know enough - but that female doctors, and particularly obstetricians, know too much.

"I've only fainted twice in my career," says Dr Gill Jenkins. Once was during her training stint in obstetrics. "It was at the delivery of this girl . . . the baby's heart had stopped . . . everything was ripped asunder and it's this horrible messy, traumatic experience . . . I was like, 'Blimey, I'm not having kids.'"

In the end, Jenkins had three children, all delivered by caesarean section (one emergency, two elective). If you've seen deliveries, she says, "you know the reality." And "maybe that's why doctors go and have caesareans - they know it is quite a risky time".

Consultant obstetrician Virginia Beckett also puts it plainly: "When I was 14 weeks pregnant I dealt with 12 stillbirths in one 24-hour shift. You can imagine that might skew your view of how to manage your labour." (Beckett has had two caesareans, the first because her baby was breach, the second was elective). On that particular shift, her baby was too small for her to feel any movement. Emotionally drained and anxious, she scanned herself in the middle of the night. She needed to know her own baby was still alive.

Beckett has worked in obstetrics for more than 16 years, but dealing with stillbirths "doesn't get any easier". As the obstetrician, you "go in with the machine and with the patient's eyes boring in to the side of your head, make the diagnosis and break the news".

Every time it happens Beckett finds it "heartbreaking, sometimes I do cry actually, not in front of the patient. You feel terrible . . . But there's nothing you can do." In the middle of a busy shift there is no time to reflect. "You can't spend half an hour coming down from every case," Beckett says, "because there will be another one along in a minute."

Complications include "abruptions, where the placenta separates and mum and baby can bleed to death. We see people having seizures with pre-eclampsia or eclampsia. We see people's uteruses rupturing when they've had a caesarean section in the past. We see acute fetal distress. We see very complicated vaginal deliveries using instruments, at which various degrees of injury can be sustained . . . All life is here as they say."

It is the obstetrician's job to control the less palatable, natural, consequences of childbirth. And they are very good at it. The UK is one of the safest places in the world to have a baby. And of the 1,917 babies born each day in this country, just 11 will be stillborn. "We know that when we work effectively we're able to make a difference and that's why we keep doing the job. When it goes to plan, you feel very positive."

And when things go badly? "You feel absolutely awful: drained and disempowered, really." Choosing a caesarean, admits Beckett, is one way of redressing this because "you realise how out of control things can be sometimes" and ultimately, "how fragile life is".

The medics making this choice are unlikely to find support among their colleagues in the midwife unit or even, in some cases, their employers. Current Nice guidelines discourage obstetricians from offering C-sections on "maternal request". Instead, natural births top the government's maternity "menu", with home births promised alongside other "normal" delivery options by 2009.

Privately, however, many obstetricians believe women should be able to choose a caesarean, if they are aware of the risks. Consultant obstetrician Sara Paterson-Brown has publicly asserted a woman's right to an informed choice because "mothers must live with the consequences". Her hospital has not since suffered a stampede of women eager for the surgeon's knife. "Women are counselled and fully informed and recommendations are made," she says. "We don't feel threatened by women expressing their choice."

Paterson-Brown won't tell me how her own children were delivered, but resolutely feels "the best way to have a baby is normally with no complications. The trouble is, you don't know if that's going to be you or not."

The vast majority of women want a vaginal birth. Just 3% of women even ask for a caesarean without medical indication. Almost 25% will end up having one anyway - largely in emergency circumstances - and a substantial number find their "normal" delivery will go seriously off plan. "There is a lot of luck involved," says Beckett, "and sometimes the luck isn't there for you." Doctors know this, lay women don't; and when things go wrong, they blame themselves.

Dr Abigail Fry remembers one birth as a medical student which turned from "calm" to "completely crazy" when a cautious doctor intervened. It became a difficult forceps delivery. Afterwards she remembers "the registrar doing the woman's stitches and saying: 'Do you think this bit, you know, should go there?' And I was like 'I don't know!' It was a mess." Unlike her obstetric colleagues, Fry chose a home birth.

"I was lucky," she says, "I really enjoyed it." She had a healthy baby boy, but some of her friends were not so lucky. As with around 15% of home births, they were forced to transfer to hospital. Having failed to achieve their ideal, they were "really disappointed, feeling like they've failed because they didn't manage it."

A recent study also found a huge polarity between pregnant women's expectations of birth and the reality. Expectant mothers need not be frightened by rare, unlikely risks, but they should be given realistic information about the pain and unpredictability of childbirth.

Instead there exists a misguided, competitive birth culture; where "lucky" or natural "birthers" are praised for their success, while mothers who "succumb" to medical intervention openly admit they've "failed". Elective caesarean births are so low on the league table they can barely be mentioned without fear of acrimony.

"Women need education," says Linda Cardozo, a professor in urogynaecology, who blames the "brand of doing it naturally" for this competitive approach as well as the trend for the "madness" of home births. "Most are perfectly safe," Cardozo admits, "but if something does go wrong you're in the wrong place to deal with it." Childbirth is a natural process, but she thinks we've forgotten it's also "a natural process for far more mothers to be damaged and far more babies to die, and medical intervention is absolutely wonderful because it's prevented that".

But this does not make Cardozo an advocate of elective caesareans. She remembers colleagues choosing them 20 years ago, but personally felt differently. "You see bad experiences in all deliveries, not just vaginal," she says, besides which, "I truly don't believe the risk is worthwhile.

Caesarean section is an operation and all operations carry a complication rate." So Cardozo did what most women in the UK do, and delivered her three children vaginally, in hospital. Two were twins, one delivered by forceps. "And I'm not incontinent - yet," she says.

Should her patient be adamant that she wants a caesarean, however, Cardozo admits that unlike in the past, she wouldn't "try too hard to dissuade her". Mainly because "of the litigious nature of the speciality I work in," she says - perhaps revealing one of the reasons why caesarean rates have doubled in the past two decades.

Natural or not, she says, the "major, major concern" of obstetricians and medics is delivering mothers and babies safely, without judgment and by whichever means. Everything else is secondary - luxurious thinking afforded by the medical advances women are now encouraged to shun. After all, "why do we have children?" asks Sher. "It's not for our own gratification, for our childbirth experience, it's because we want to have a child."

· This article was amended on Tuesday July 15 2008. We misspelled the name of a professor of urogynaecology, who is also a consultant gynaecologist. She is Linda Cardozo, not Cardoza. This has been corrected.