Table II.

Demographic data^*

	Percentage ± SE
	2001–2002 (n=7,878,870)	2011–2012 (n=7,437,199)
Age, years
12–18	6.3 (0.1)	5.6 (0.1)
19–25	38.9 (0.5)	33.5 (0.5)
26–35	48.7 (0.4)	49.1 (0.4)
36–45	11.0 (0.2)	11.5 (0.3)
46–55	0.07 (0.004)	0.09 (0.005)
Payer
Medicaid/Medicare	37.1 (1.0)	44.4 (0.8)
Private insurance	56.6 (1.2)	50.0 (0.8)
Self	6.1 (0.5)	5.4 (0.2)
Mode of delivery
Vaginal	71.6	65.1
Vaginal birth after caesarean	2.7	1.7
Repeat caesarean	10.3	15.3
Primary caesarean	15.5	17.9
Multiple birth	1.6 (0.04)	1.8 (0.03)
Hypertensive disorder in pregnancy (any)	6.9 (0.1)	8.5 (0.1)
Pre-gestational and gestational diabetes mellitus	0.7 (0.03)	1.0 (0.02)

^*All demographic variables p<0.001 between two time periods.