Table 1

Characteristics (per cent) of the 554 234 pregnant nulliparous women by ethnic group

Ethnic group	Dutch	Other Western	Turkish/Moroccan	African	South Asian	East Asian	Other non-Western	Unknown	Total	χ², p value
Pregnant women, n	460543	15007	34973	11605	5853	10675	12541	3037	554234
Pregnant women (%)	83.1	2.7	6.3	2.1	1.1	1.9	2.3	0.5	100.0
Maternal age at birth (years)										<0.0001
<20	2.3	4.3	7.7	19.9	6.7	7.4	10.9	6.0	3.5
20–24	12.6	20.1	43.8	33.6	29.3	22.0	26.0	21.7	15.9
25–34	74.2	62.4	43.6	40.9	56.7	59.4	52.9	63.7	70.2
35–39	9.8	11.7	4.2	4.7	6.4	9.7	8.7	7.7	9.3
≥40	1.1	1.5	0.9	1.0	1.0	1.6	1.4	0.9	1.1
Mean	29.1	28.5	25.2	24.6	26.7	27.8	26.9	27.6	28.6

Urbanisation
Very urban	17.0	35.9	48.7	55.3	55.1	33.6	41.6	32.4	21.7	<0.0001
Urban/rural	64.1	55.6	49.1	40.9	42.0	59.7	51.7	57.1	61.8
Very rural	18.9	8.5	2.2	3.9	3.0	6.7	6.7	10.5	16.5

SES
High	10.4	9.7	2.9	3.8	6.8	9.5	7.2	7.7	9.6	<0.0001
Middle	83.3	74.8	61.4	57.2	59.3	72.7	69.7	76.7	80.3
Low	6.3	15.5	35.7	39.1	33.9	17.9	23.1	15.5	10.1

Low income	35.3	36.8	61.1	64.1	58.2	42.2	46.8	42.3	38.2	<0.0001
Booking visit ≥ 18 weeks	13.2	23.0	20.4	32.7	22.8	24.0	28.4	17.4	15.0	<0.0001
Heavy smoking	0.6	0.4	0.3	0.2	0.1	0.2	0.1	0.4	0.4	<0.0001

Pre-existent disease
Essential hypertension	0.6	0.3	0.2	0.5	0.5	0.2	0.3	0.2	0.5	<0.0001
Diabetes mellitus	0.2	0.1	0.2	0.3	0.6	0.1	0.1	0.0	0.2	<0.0001
Other endrocrinological diseases	0.4	0.5	0.3	0.2	0.7	0.3	0.4	0.2	0.4	<0.0001
Systemic disease	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.0	0.1	0.03
Cardiac disease	0.1	0.1	0.1	0.1	0.2	0.1	0.1	0.0	0.1	0.46
Trombo-embolitical disorders	0.3	0.1	0.1	0.2	0.2	0.1	0.1	0.1	0.2	<0.0001
Psychiatric disorders	0.3	0.2	0.4	0.4	0.3	0.2	0.3	0.1	0.3	0.002