Apparently there's a saying going around Microsoft now; bowdlerized, it's, "the average person has one breast and one testicle." It's a caution against relying on statistical models without examining the context.

I strongly suspect that the reason second-child home-births have the same complication rate as hospital births is that those who were most prone to complications (as demonstrated the first time) went to the hospital. This skews the result heavily... indeed, I'm surprised that home-birth for second children doesn't show a greater safety rate because of that bias.

Of course I haven't seen the study design or how they controlled for this so perhaps I'm being unfair.

-- Steve's not a stats genius in any case.