Table 1. Maternal, pregnancy, and neonatal characteristics of each group.

		1) dilator	2) balloon <40	3) balloon ≧40	4) overlapping
		N = 4650	N = 4103	N = 6616	N = 1994	p
use of uterine stimulants	n (%)	4126 (88.7%)	3445 (84.0%)	5968 (90.2%)	1846 (92.6%)	<0.01
maternal height (cm)	mean±SD	158.7±5.6	158.5±5.6	158.3±5.6	158.4±5.6	0.01
maternal weight (kg)	mean±SD	64.0±10.2	64.9±11.2	66.0±11.3	66.2±11.3	<0.01
maternal BMI	mean±SD	25.4±3.8	25.9±4.2	26.3±4.2	26.4±4.1	<0.01
maternal age	mean±SD	32.7±5.4	32.0±5.8	31.6±5.8	32.4±6.0	0.02
gestational age (week)	mean±SD	39.7±1.4	40.0±1.3	40.0±1.3	40.0±1.4	0.03
baby's weight	mean±SD	2998±431	3053±452	3055±454	3038±477	<0.01
baby's sex (boy)	n (%)	2311 (49.8%)	1977 (48.2%)	3250 (49.1%)	945 (47.4%)	0.27