Table 1

Characteristics of women enrolled in the pregnancy-monitoring system by gestational hypertension status; China, 1993–1996

Characteristics	Gestational hypertension group (n=19 115)		Non-gestational hypertension group (n=180 988)		P value
Characteristics	n*	%	n*	%	P value
Age at pregnancy, (years, mean (SD))	25.04 (3.34)		24.86 (3.21)		<0.001
Body mass index at first visit (kg/m², mean (SD))	20.77 (2.25)		20.50 (2.09)		<0.001
Primiparous	16 277	85.15	149 967	82.86	<0.001
Han ethnicity	18 977	99.28	179 670	99.27	0.923
Folic acid use	10 245	53.60	94 874	52.42	0.002
Education level					0.123
High school or higher	2014	10.54	20 045	11.08
Junior high school	11 380	59.53	107 253	59.26
Primary school or lower	5672	29.67	53 175	29.38
Unknown	49	0.26	515	0.28
Occupation					<0.001
Farmer	10 930	57.18	106 992	59.12
Factory worker	5409	28.30	49 257	27.22
Other†	2754	14.41	24 480	13.53
Unknown	22	0.12	259	0.14

*Values for certain characteristics may be lower than the total numbers of subjects with or without gestational hypertension because some data were missing.
†Other includes businessman, teacher, day labourer and civil servant.