It's Nothing Personal, But...
A few weeks back, I was helping my wife Kat study for another one of her midwifery exams. This one was about the actual process of birthing, and everything that can go wrong, and how to track the infant's movement as it's being born. Of course, me trying to quiz Kat on the process of birth is like me trying to quiz magicians on their stage act: I don't know enough to even frame intelligent questions, let alone figure out whether or not their answers are correct. To counter this problem, Kat had made up some flash cards, and I was quizzing her as we drove back from a trip out of town.
So I'm trying to decipher these alien words which she's scribbled on the backs of colored flash cards, and I get to one about what triggers birth. One of the reasons was, and I quote, "pressure on o's." After a second, I realized I knew what that meant. "Pressure on the internal organs," I announced. Boy, did that get me a look; I might as well have said, "birth fairies sprinkle magic dust on the mother's tummy." After I read the other things on the card and Kat deduced the subject, we sorted out the actual answer (pressure on the cervical openings), and kept going. But I think maybe I'm on to something here.
After all, think about it. Although at first the foetus doesn't take up very much space, it keeps growing, and eventually it's pushing everything out of its way. In some cases-- you've seen them, I'm sure-- you end up with a small mother that has a baby so large that you can't figure out how it fits in there at six months. But anyway, all those lower-abdominal organs get shoved around by this interloper which is continually grabbing a lot more than its fair share of the nutrient stream.
So I bet birth is actually when all the organs get together and throw the baby out. It's a lot like what happens when one of your roommates is a jerk, taking up a lot more than his fair share of spaces and always raiding the fridge but never buying any groceries. Finally the rest of you get fed up with him and tell him that maybe he ought to find alternate living arrangements.
It's the same thing with birth. It usually takes about nine months, but sooner or later the organs decide that enough is enough, and send out some signal which is the chemical equivalent of, "Look, kid, you're cute and all but you've become a major pain. You're cramping up the entire place, all you do is just lie around all day kicking us, you suck down more food than the rest of us put together, and you haven't paid your rent since you got here. We're really sorry, but you're going to have to find someplace else to live. Now beat it! And don't let the cervix hit you in the ass on your way out."
(This is probably why babies tend to cry right after they've been born. They start life by having been rejected by the internal organs, plus now they have no idea where they're going to live. How would you feel in that situation? You'd be crying your eyes out.)
This whole theory also explains false labor. In these cases, when the organs insist the baby move out, the baby signals back that it's really really sorry and that it'll clean up its act. They argue about it for a while, and eventually the organs relent. Maybe they believe in second chances and all that, plus maybe these particular organs can't handle conflict. At any rate, everything goes back to normal for a while, and when the organs finally realize that things aren't going to get any better, they try again, only harder this time. Sooner or later, they make it stick, but sometimes it takes a few tries.
Of course, being pre- or post-date is simply a reflection of the tolerance level of the organs. Some are less patient than others.
In fact, sometimes the organs really want the baby out, but the baby flatly refuses to leave. This is when you usually end up with a Caeserean section, in which the doctor plays the role of a sheriff's deputy with an eviction order. It's messy and painful, just like in real life, but sometimes it has to be done. You just hope that everyone can recover and move on once it's all over.
And the part of the midwife, in all of this? Social worker and life counselor, really. You're there to catch the baby just after it's been kicked out of its place to tell it that everything's going to be fine, and that you have a great new place for it to stay. All you have to do is hand it over to its new landlord-- the mother-- and hope everything works out for the two of them.
So there you have it: the real reason birth happens. Aren't you glad someone finally came out with the truth? You're welcome. Feel free to send me lots of research grants, which I'll use to study birthing practices in as many tropical-island cultures as I can find.