Call the Midwife has been an extraordinary success for the BBC. With more than eight million viewers, it is the highest-rated original BBC drama series since records began. If you imagine the schedule as a Hollywood blockbuster, this is like Nicolas Cage (Sherlock) and John Travolta (Doctor Who) fighting to the death, only to find Cameron Diaz effortlessly swooshing past them to save the earth. One Born Every Minute, meanwhile, is on its third series and has been exported to the US. It netted 800,000 new watchers in one week last series, just for one flamboyant birth. (In fairness, it can't be attributed to any particular birth. It's just extremely popular.)

People who understand telly by genre will note that these are two totally different experiences, no more similar than Upstairs, Downstairs and Celebrity Big Brother. But something unmistakeable has happened: the act of labour, the very nuts and bolts of bringing forth life, has turned into a dramatic event in itself. TS Eliot was right when he said: "Birth, and copulation, and death. That's all the facts when you come to brass tacks." And while, in recognition of that, copulation and death are pretty much all that happen in most telly (sorry, copulation, death and chat), birth has never had a look in.

That's not exactly it – of course people have had babies on television, but the birth is never the drama in itself, it is always just the catalyst for some other plot twist, from a maternal death to a paternity question mark. As Cathy Warwick, general secretary of the Royal College of Midwives, notes wryly: "What we don't like is the soaps and what they do. You don't often see a nice, normal, ordinary birth. It always has to be turned into a huge trauma."

In the amplification of birth disaster, soaps are nothing compared to films, where labour is only ever the prelude to terrifying jeopardy. I'm trying to back that up, but for some reason my brain will only give me a picture of Natalie Portman dying in Star Wars. Nevertheless, I think you'll concede without a huge amount of exemplifying, that labour on its own is not drama; labour has traditionally been the medical-drama equivalent of drunkenness: interesting only to the people in it, or to the rest of us when it leads to calamity. And this is weird, for a number of reasons: first, as Pippa Harris, the executive producer of Call the Midwife, says: "Everyone goes through it, you're either born or your child is born. Whereas, with a lot of medical things … you're never in your life going to get run down by a bus, and yet that's depicted all the time."

Besides being universal, it is so very obviously dramatic, so bookended by recognisable beginnings and a heartwarming end. "Born in pain, followed by joy or tragedy and anguish," says the narrator at the start of Call the Midwife. And that, right there, is more emotion than we've seen in 25 years of Home and Away.

So the obvious explanation is that, previously, the off-screen relegation of parturition was the result of straight sexism, and its new primacy is a good sign. Certainly, Harris recalls: "When we started showing the first episodes to journos and critics, people did say, 'Do you think you're going to have problems because men won't want to watch this?' You'd never have the opposite question asked. I worked on a programme called Warriors, which was about British peacekeepers in Bosnia. I was never asked if having too many men in the show was an issue."

It is more than just a change of perspective, although it surprises me (post-Golden Girls!) how rare it still is to have a cast that is not just mainly female, but also crosses the whole range of the sex, right through to the ones who aren't even young. It is also a revolution in the way birth is presented; typically, labour has been shown very squeamishly and primly, as though it's a bit like having a splinter removed. That chasm between the lived experience and the way it happens to Jennifer Aniston (just as a for instance) has probably been amusing women since the dawn of television (in a bitter way).

In this respect, One Born Every Minute is the really radical departure, its break with convention being its whole point – proceeding from the fact that, in a state of extremis, nobody could sanitise or act, even if they wanted to. When you watch it, of course, it's not that straightforward. Sociologist Jan Macvarish says: "I think it is evident that the subjects play a certain role – dads as insensitive fools, mums as howling maniacs." It's hard not to give the camera what it wants, to fall into roles that people will recognise. So you'd struggle to make a case for this as a purely realistic birth experience. And yet it's obviously a world away from the sanitised norm. It occupies that no-man's land that sinks all reality TV shows. There comes a point where bringing the cameras closer doesn't make it any truer, but rather, separates the viewer from the truth by polluting the authenticity of the subject. But anyway.

That's something for Endemol to worry about. At least in OBEM, they have a baby at the end, all gunk and unselfconsciousness, and I never don't cry. A friend said: "My mum always used to cry whenever a baby was born on telly, and I used to think it was absolutely pathetic. But now I'm exactly the same." So in that respect, the question about whether labour is "women's telly" is a reasonable one: the reliability of that emotional response might be something you'd only get from someone who'd been through childbirth. In terms of the schedule, though, this is quite a large audience, given that they are always watching telly because they can't get a bloody babysitter.

Not really as a response to OBEM, just because it is quite classy, Call the Midwife also has a gritty, warts-and-all approach. Harris points out that they can't show that much, because it's pre-watershed. But the detail is so carefully observed, right down to the noise it makes when you clamp an umbilical cord, that it marks a turning point in drama, away from a bit of panting under a sheet, towards a more realistic picture of a totally appalling, cataclysmic life event. Yet I think there's something more here than just the exigencies of the story; there's an appetite for birth to be rendered realistically, as though its proper eventfulness has been recognised.

Where once the wedding day was thought of as a woman's day in the sun, the fruition of all her efforts, that's now been usurped by giving birth. And this does not represent the uncomplicated evolution of a new parity between the sexes; rather, it illustrates a new idea of birth, and it is not one you could immediately pigeonhole as either evolved or retrogressive. Jennie Bristow, researcher in parenting culture at Kent University, elaborates: "There is this general heightening of the birth experience. And of course that partly goes along with a general collapse of privacy.

"When I was younger, people used to go queasy at the idea that you'd take photos. And even besides the physical exposure, most people would have balked at having the process on display. But birth has become much more an experience that's 'all about me'. People attach a great deal of identity work to the experience of giving birth. There is this mystique that you should be a particular kind of mother, a modern day superstition that if you're a good person, a positive person, then you'll have a good birth and a healthy baby. It's this bizarre notion that input and outcome are connected."

This theme is reiterated gustily by Dame Lorna Muirhead, former president of the Royal College of Midwives. If you were to talk to her for five minutes, you would want to go back in time and have her deliver all your children. But she is no longer in clinical practice, so don't do anything hasty. "I've seen women who have looked absolutely miserable on the second day of the baby's life, and I say, 'You don't look very happy.' And she might say, 'I didn't want it to be like that, I wanted it to be natural.' And I would say, 'You wanted a beautiful baby.' This is an ideology of midwifery: that which is allowed to proceed without intervention. I so abhor that. I really do. It's safe because of the things we do, it's not because of the things we don't do. A midwife's role is not natural childbirth, a midwife's role is normal childbirth, and there's a great difference between the two."

Natural childbirth having become this ideal, the act itself is now the life-affirming event; traditionally, it would have been seen as a means to an end, whereas the life-affirming bit came when it was all over. Muirhead ascribes the change to the 1970s battle between "medicalised" birth (and there's an interesting counterpoint, culturally, here in Betty's birth scene in Mad Men, a kind of dreamscape 60s horror show where she's so dosed up to the eyeballs on pethidine that all she can perceive is a load of masked men with huge metal instruments) and the feminist drive to reclaim the process of labour. Bristow takes up this argument: "In the 60s and 70s, there was this scandal of hospitalised birth, and the idea that it had to be made more about women and less about doctors. Which, you know, in one way was fine, but it was formed by those feminist self-identity ideas which, I think, have become part of the reason why it's now got so much mystique attached to it, but at the same time it's become very self-absorbed."

The curious anomaly here is the separation of mother and foetus in the consideration of labour. According to Edward Shorter's Women's Bodies, medicine was never interested in the foetus as a stand-alone entity until maternal mortality rates dropped. And this makes perfect sense – medically speaking, jeopardy to the mother is indivisible from jeopardy to the foetus until parturition is over. So it's the relative safety of modern labour that has individualised it, made it the woman's experience rather than a two-player game. Furthermore, it was not just 70s feminism, but also a more conservative drive to reinforce the fact of women's biological differences, that conveniently dovetailed with the natural-birth agenda to create an idea of labour as the very pinnacle of womanhood, the epiphany at which they experience total fulfilment, total self-expression. And that is sort of where we are now; until things go a bit awry, and then you would see all your womanhood drowning in a boiling sea for a bit of modern medicine.

So birth has taken centre stage, and just to see its drama acknowledged is somehow amazing; yet what might look like a straightforward cultural evolution is actually fraught with new delusions, new disconnections between the ideal and the reality, new disappointments waiting to happen. It's good telly, though. You can't argue with good telly.