Aaaah, hospital pushing, always gives me sympathy hemorrhoids. All that frantic coached pushing makes me involuntarily bear down meself.
re; pushing supine. I see a LOT of women choose this position on their own. Usually, if they're not in water, they walk, rock, sway, sit on the toilet, hands and knees, whatever, and then say, "I'm tired, I want to lay down!" They lay down, usually on their sides, fall asleep for a few minutes (or even a few hours!) and wake up, roll onto their backs, (or, less frequently, onto hands and knees) and push the baby out within minutes.
I don't really think pushing while laying supine is a problem, clearly the overwhelming majority of women world wide do push babies out while lying on their backs, whether or not it's by choice or by protocol. I think it's the forced, coached pushing that starts as soon as she's complete that makes pushing difficult and prolonged. We all know there's a whole lot of molding, rotating and repositioning (as well as a well-deserved break from contractions) that happens after she reaches fully, and if she's not ready to push then no amount of coaching, counting, holding breath, tugging, or stretching is going to make it happen. What's the big rush to bring the baby down?
I was trained to coach pushing as soon as the woman was complete (and yes that meant lots of VE's) but since I stopped checking for dilation and stopped coaching, I rarely have a second stage that lasts more than 20 minutes in primips and 2-3 contractions in multips. Usually, the baby's head appears without warning or fuss and Dad has to scramble to receive the baby!
Rarely do I see a woman choose to squat on her own, or stay squatting if she does choose it, it's tiring and the pressure is overwhelming. I rarely see women choose to stay on the birth stool or toilet for pushing, either, they usually jump up and stand or lean forward onto hands and knees or more often the runner's starting pose.
I guess I don't see any birth position as inherently better or worse than another, but I do believe forced, coached pushing is counter-productive, exhausting, and painful. A whole lot of work that does nothing to hasten the process and makes mama/baby tired and stressed.
I don't think pushing a baby out is like moving your bowels at all. I tell women pushing is like throwing up, in reverse. Once the urge strikes, nothing or nobody is going to stop it. You can usually hang on to your poop, but when you gotta puke, it doesn't matter if you're alone in the woods or on stage at Carnegie Hall, you're gonna puke.