I asked my midwife about it (a CNM) and I was a little bit put off by her response. She said that she doesn't think there are any benefits, but there is a big drawback. That is that there is no way to prepare for meconium in the fluid if you don't see it during the rupturing of the membranes. She also suggested that the baby would inhale the fluid before the bag was ruptured.
I am very confused by those statements. I know that I was much more comfortable with my late rupture baby than with the others, and that seems logical. Instead of hard skull on spine action (as my babes are born all occiput posterior), there's sort of a water-barrier there. Plus, I didn't think the baby took the first breath until he/she hit air, which would be after the sac was removed anyways.
I thought I'd be set with a midwife for a good birth experience. Now I'm concerned a little. I'm also scheduled for an OB consult next week (37 wks) in which, as she described "we'll look at the baby in an ultrasound to make sure that baby's not too big and that I'm not high risk."
So, a little nervous, now.