Baby #1: 10 hours of steady contractions, 2-3min apart, 45-60seconds long = zero centimeters. 36 hours of this got me 3cm. Total labor was 68 hours, with only 20min pushing.
midwife swore it was a fluke and wouldn't happen again.
Baby #2: Was a fingertip dilated going into it, 10ish hours of labor, arrive at the hospital puking my guts out, convinced I must be in transition...nope, just barely 1cm. Ended up getting 2 epidurals (1st one stopped working, 2nd one only worked on one side) then a spinal block, 20min of pushing and out popped a 10lb baby. 26 hours total.
They tell me that baby just doesn't come down to push their head on the cervix so it doesn't dilate quickly. Am kind of terrified of having another long labor - though this pregnancy has been so easy and such a breeze so far, maybe it will be different. With my first two I would only make progress if I was heavily drugged up - like with the first they gave me morphine and I went from 1 to 3 in a few hours. They were all excited and said I should just up and move around to keep it going...nope, 5 hours later I was still a 3. I've decided that if I show up at the hospital and am solidly well along - 5-6cm at least, I will keep it moving naturally, but if it looks like it's going the way it's gone in the past I want all the drugs I can get.