Table 2. Duration of labor in hours from one-centimeter dilation to the next, by parity.

		Parity 0		Parity 1		Parity 2+
Cervical dilation cm	Cervical dilation cm	Duration in hours (min-max)	n	Duration in hours (min-max)	n	Duration in hours (min-max)	n
3	4	0.83 (0.14–4.97)	8 876	0.47 (0.05–4.65)	3 566	0.52 (0.05–5.05)	2 152
4	5	0.89 (0.15–5.26)	17 425	0.38 (0.04–3.82)	7 550	0.43 (0.04–4.62)	4 113
5	6	0.68 (0.10–4.55)	19 017	0.23 (0.02–2.90)	8 962	0.19 (0.01–3.23)	4 454
6	7	0.48 (0.06–3.82)	17 969	0.12 (0.01–2.25)	8 887	0.10 (0.01–2.37)	4 135
7	8	0.33 (0.03–3.62)	16 599	0.08 (0.00–1.94)	8 470	0.05 (0.00–1.85)	3 717
8	9	0.24 (0.02–3.00)	16 326	0.04 (0.00–1.58)	8 233	0.02 (0.00–1.27)	3 500
9	10	0.18 (0.01–2.66)	14 611	0.02 (0.00–1.18)	5 990	0.01 (0.00–1.03)	2 357

Data reported as median hours (5^th, 95^th percentiles)