Yeah, very true. There's so much more to consider than just basic lung maturity. Someone pointed out the point at which they will 'stop delaying labor', and I think that's moreso what it is "supposed" to be used for... just not necessarily what it is used for.
I'm in the same boat though... I think 37 weeks is the earliest I'd stay home, though I'd prefer closer to 38. Even that seems to early for me, but that's probably skewed by the fact that most babies in my family come late, or at most, 2-3 days prior to the due date. My aunt had twins years and years back, and they even made it to 40 weeks and were both around 6lbs. In my head I have this babe coming a few days post EDD, and that sounds perfect to me. I'm going to try really hard not to consider myself "overdue" until I hit 41weeks 3 days, which is what has stuck in my head as being "average first time mom" gestation. Though I do think they revised that to be 41/1 sometime in the past few years.
Katrina-- I believe they do count that multiple births in the 'average'. I remember reading something about how that's one of the reasons that the average length (and birth weight in turn...) has gone down, is because of the increase in assisted pregnancy technology (ie IVF and whatnot) has increased the number of multiple births... which decreases the average gestation and birth weight. It's not accurate though, and that sucks! It gives people a false sense of security, and leads them into believing things like 35 week births are "not that uncommon" or dangerous for the baby.
Case in point, I had a semi-fight with my SIL the other day about homebirth as I mentioned, and since we're forced to being in the hospital, I told her I wanted to go home ASAP after the birth, once I've had a chance to shower, have a nap, eat and rest for a few hours. She was appalled because "you never know what's going to happen, and not all emergencies happen at birth". Her example? The fact that her 35 week daughter had her lung collapsed in the NICU at 36 hours old (after having an NG tube in for those 36 hours, with intermittent suctioning). She flat out told me "it had nothing to do with her being a preemie". I was shocked. I mean I --know-- that things can happen after birth. But for her to honestly not think that her 35 week old daughters lung collapsing had nothing to do with either the hospital interventions or her being 35 weeks was just... mindblowing to me. Moms are led into a false sense of security by a simple lung maturity test, and then think that means the baby is all hunky dory otherwise. But 35 weeks is still not when babies are designed to come out (nor at 37 weeks, which is really what the point is.... but you catch my drift).
It's a dangerous statistic to use, and yeah, it makes me sad to see people put so much weight on it.