Table 2.

Distribution of Selected Characteristics of the Study Population (N = 10 041), Urban China, 2010–2012

Characteristics	Normotension (n = 9,676)		Preeclampsia (n = 365)		P-valuea
	n	%	n	%
Maternal age (years)
<25	1536	96.1	62	3.9	<0.0001
25–29	4700	97.3	131	2.7
≥30	3440	95.2	172	4.8
Maternal employment
No	4673	95.6	213	4.4	0.0002
Yes	5003	97.1	152	3.0
Monthly income per capita (RMB)
<3000	4847	95.2	242	4.8	<0.0001
≥3000	2911	97.9	84	2.1
Missing	918	95.9	39	4.1
Highest education level
<College	3743	94.6	213	5.4	<0.0001
≥College	5759	97.5	145	2.5
Missing	174	96.1	7	3.9
Prepregnancy body mass index b
<18.5	2024	97.9	43	2.1	<0.0001
18.5–23.9	6380	96.6	222	3.4
≥24.0	963	92.4	79	7.6
Missing	309	93.6	22	6.4
Weight gain during pregnancy
<15 kg	3712	97.6	92	2.4	<0.0001
15–18.5 kg	2230	97.4	59	2.6
>18.5 kg	3351	94.7	187	5.3
Missing	383	93.4	27	6.6
Smoking (passive and active) during pregnancy
No	7811	96.5	286	3.5	0.26
Yes	1865	95.9	79	4.1
Alcohol consumption during pregnancy
No	9655	96.4	384	3.6	0.38
Yes	20	100.00	0	0.00
Physical activity during pregnancy
No	1682	96.2	67	3.8	0.63
Yes	7994	96.4	298	3.6
Parity
Primiparous	7005	96.7	239	3.3	0.004
Multiparous	2671	95.5	126	4.5
History of gestational hypertension
No	9634	96.5	345	3.5	<0.0001
Yes	42	67.7	20	32.3
Maternal diabetes
No	9591	96.4	357	3.6	0.010
Yes	85	91.4	8	8.6
Multiple birth
No	9447	96.9	307	3.2	<0.0001
Yes	229	79.8	58	20.2
Gender
Male	5102	96.8	168	3.2	0.010
Female	4546	95.9	197	4.2
Missing	28	100.0	0	0.0

^aCalculated by χ²-analysis without accounting for missing data.

^bWeight (kg)/height (m)².