A possible minor nit-pick: I was under the impressions that the majority of labor discomfort is from dilation of and passge through the cervix, not the vagina.
… furry elephant brains… I’ve had that problem before…
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IMHO, evolution kept up just fine with the big baby head thing - a) the baby’s head collapses during birth to help (cone-head!), b) the baby rotates during birth to make itself match the size/shape of the pelvic outlet best, c) baby is born very prematurely to get as small a head as possible (compared to other species). d) the pelvic hinge opens up the pelvic outlet dramatically if you respond to the instinct to squat. e) the baby actually helps itself be born (one of the reflexes that causes them to arch their backs and straighten their legs is used during contractions to help expulsion). BTW, evolution doesn’t CARE if it is uncomfortable, only if enough offspring survive.
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Childbirth is more complicated the more we mess around with it. The World Health Organization considers a c-section rate of about 12% to be normal. That means the vast majority of women will not have complications that will seriously injure or kill either the mother or the child, period. So why are the complication rates so high in the US and in some other countries? Compare against births in less ‘advantaged’ places (such as the Navajo reservation), and you’ll find that the births that are not treated as ripe for intervention have far less go wrong with them. There’s also a culture of negativity about birth in the US popular culture, little social support of behaviors that would support better births, etc. Part of the rate of complications is generated by our approach to pregnancy and birth, our diets, our lack of exercise, etc.
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Often, the ‘complications’ we are told about are things for which there are other solutions, the solutions are just not understood by the caregiver, or they’re a pain in the butt to do. For example, one woman I know online had a ‘stuck’ baby. That is, after 4 hours of being complete, the baby wasn’t descending. With standard medicine, that’s a c-section issue for a major complication. With her case, one of the two attending midwives worked out (much of the working out taking place during those four hours) that the kid had her hand pushed up under her chin, and was coming down ‘military’ (head not tucked chin to chest). She did some positional messing around with mom, and they got her baby’s hand moved, and her head tucked, and she was born (launched!) a few minutes later. It was a pain in the butt to do, and needed real knowledge that most attendants don’t have. Why do I include social knowledge as part of the evolution question? Because we evolved as social creatures. We’re ‘designed’ to respond to our social peers in the process of labor. If that weren’t so, then having a doula present wouldn’t drop the c-section rate to 6% (in at least one study, and similar results on not needing pain meds, too). We have more functional labors in the presence of experienced and caring peers. We traded a more instinctive reaction for a social network. Though I’ve also heard of animals freaking out in their first labor, too.
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Some things are called complications when they are just variations. Posterior birth isn’t a complication, it is a variation. A really rotten variation, but not usually deadly. Evolution only cares about dead or too damaged to survive or protect/nurture offspring. Again, social culture comes into play evolutionarily… we know that even very early cultures took care of injured and disabled family members. Variations that might cause more damage or longer recoveries are less forced out of the gene pool. So we’ve got a lot of variations. But even those can often be managed in such a way as to not cause damage to either mom or baby.
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Women today are hardly in as good physical condition as most farm animals, and certainly not usually in as good condition as most wild animals. Consider the fact that many wild critters are weeded out just because they aren’t really highly fit. We don’t weed out humans under those conditions, so our population isn’t a good match - you can’t compare birthing between average modern humans and highly fit wild animals that are already the top 40-50% (guestimate) of their population pool. Your condition has a huge impact on your capacity to birth ‘easily’ (note the quotes). Also, we’re used to not managing through pain, not relying on our native coping mechanisms for pain management… we rely on drugs. So when we come up against a decidedly uncomfortable situation, pain isn’t managed by native process. We’re just not in enough practice to rely on it. Beyond that, in the US we’ve lost most of the birth culture that would help us manage better - for example, most of our mothers don’t know how to change positions to help different stages feel better anymore (Cochrane Medical Abstracts found that standing for the second stage of labor significantly reduced maternal pain, for example - but I know very few moms who can pass on that little home truth to their daughters, because they weren’t permitted to birth in that position!).
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The negative birth culture also leads to more anxiety, and more anxiety leads to more tension, and more tension leads to more pain. Having tried deep relaxation for labor management, even the slightest tension in the back of my hands or forehead made things HURT everywhere. Really trusting it and relaxing into it and it was hard work, uncomfortable the way a really hard workout is uncomfortable, but not actively awful. Yeah, that’s beside the point on complications, but it isn’t beside the point on the pain of birth thing mentioned in the replies. Birth isn’t designed to be easy - our babies are so premature that we can’t afford for them to ‘fall out’ too soon. That’s true for other animals, too, of course - we’re timed pretty close to the line for what is survivable, for all species (some just have to be able to run fast right after birth in order to survive). You also have to know how an animal responds to discomfort and pain to be able to assess how ‘painless’ animal birth is. In watching animals birth, many are definitely working hard enough to be uncomfortable, they pant or sweat, they yelp at expulsion or purr with distress. It isn’t ‘supposed’ to be easy, just within our capacity to cope and survive and not kill ourselves the next time we realize we’re pregnant, or give our position away to predators.
I’ve read Soranus’ Gynecology (2nd c. AD greek physician, first real scientific book on obstetrics). Overall, back then, it appears that most births were considered high effort, requiring good support both physically and emotionally (reassurance and a positive attitude in the midwife was noted to have a significant impact on maternal judgement of pain and difficulty). There were complications, often enough to give instruction on the resolutions (sorry, he didn’t keep stats on rates), and variations that led to difficult births. Especially with first births. But there were also ways of handling those, even then. Babies died. Mothers died. Just like farm animals die sometimes without good help, just like wild creatures also die occasionally. I suspect that human maternal death rates are somewhat higher because of the risk of a dead fetus being retained (infection and gangrene from retained stillbirth were issues in Soranus’ day)… and even back then, Soranus found that women who were not in good physical condition, who ate poor diets, and who feared labor or were suffering any emotional upset had the most risk of dysfunction.
(one way evolution backfires on us on the baby head size thing is that the close alignment of the baby size and shape to the maternal pelvis means that expulsion after fetal loss is a bit trickier.)
Still, the death rate for human babies normally appears pretty similar to other animals that I’ve seen - a lot of first borns died (by comparison to later births), just like they do in horses, cattle, and other critters. A fair number of mothers died, too - those 12% c-sections are a significant number of survivals (or freedome from major damage) that otherwise wouldn’t happen.
While we’re now derailing evolution with medicine (just like we’ve already done with social culture), we haven’t been doing so long enough for us to have evolved into a species of truly terrible birthers. Evolution takes longer than that. Maybe we’ve got some genetic drift happening, but not evolution. We’re carrying around more of the genes for bad birth experiences, but the rates overall are pretty stable - we’ve got the medicine to prevent disasters (and to cause a few along the way), but overall, women who are in good shape, who know how to use their bodies, who are attended by people who understand birth and don’t over-react to normal variations out of fear of litigation, generally appear to have that ‘normal’ rate of problems - about 10-15% have problems of some sort that require significant intervention. That still gives our species a solid B grade for birthing. Not bad for a species that isn’t weeding out the unfit before reproductive age! And considering how many kids one can have (a 20-year fertile zone), having a few survive to adulthood is pretty good odds. That’s all evolution cares about.
(oh and yes, the most pain is from dilation effort - the kid’s head presses on the relevant nerves while passing down the vagina, so you can feel them there, but for most women it doesn’t hurt until they get to the exit… that part burns, but again, with good support and good positioning, it doesn’t hurt enough to keep you from doing it again.)
Is the incomplete formation of the infant’s head a possible evolutionary response to the problem of the size of the birth canal? Are other primate’s, infant’s, heads incomplete like this?
Bob
Well, head, in the previous post really should be skull.
Bob
The skull is still unfused so that the plates can overlap and squash the head into a smaller size to get through. So yes, the baby’s skull immaturity is part of the evolutionary reaction to getting through the pelvic opening (which is the bony part - the birth canal is technically the vagina, which stretches just fine for most women, regardless of head size, as long as the baby doesn’t stick a hand up there and make for a non-round shape).
I don’t know the figures but the UK and NZ, who have a high % of homebirths, have some of the lowest rates of complications and fatalities associated with childbirth.
I think a great way to freak out a birthing mother would be to remove her from her home, drag her to a hospital to inhale disinfectant, and have some obstetrician induce the birth so he can get a good nights sleep and have a good round of golf tomorrow.
Even if it takes 80 hours let it come naturally.
I was all set to talk about hospital-induced complications to natural childbirth, but hedra beat me to it 
In other words, what hedra said.
I think a great way to relax a birthing mother (especially first time) is to take her to the hospital where she can be surrounded by people who are capable of immediately responding to any danger to herself or her child.
There are some women’s hospitals where you get the best of both worlds. Calm birthing rooms with no medical equipment if not necessary, but the benefit of immediate professional medical care if something does go terribly wrong.