I requested mine as soon as I found out I was pregnant.
They didn't give me one. *sigh*
I knew ahead of time I would want one, so it was already set up that I would have one.
I know it will vary, but I *think* you can still get it up to about 8cm?
As for it wearing off, I was in labor with my youngest for 15 hours and it didn't wear off. It's on a slow drip so it was constant. They did turn it down when I started pushing and off when the baby crowned.
Not a problem here as my first was born with 7 1/2 hours of labor and 50 minutes of pushing (induced)...my second was born after 2 1/2 hours of labor and 1 1/2 pushes (induced) my third I went into labor on my own...hence the 15 hours. He was born 26 minutes after they broke my water.
After they turned it off at crowning, I was up and walking around within 3 hours. A little wobbly, but walking.
at 4:34 PM on Jan. 13, 2009