Table 2

Selected sociodemographic characteristics of the study population: singleton births with a gestational age of 28 weeks or more in Denmark, Finland, Norway and Sweden, 1981–2000

Characteristics	Denmark (n=1182888)				Finland (n=832640)^*			Norway (n=1018572)				Sweden (n=1974134)
Characteristics	1981–1985	1986–1990	1991–1995	1996–2000	1986–1990^†	1991–1995	1996–2000	1981–1985	1986–1990	1991–1995	1996–2000	1981–1985	1986–1990	1991–1995	1996–2000
Maternal education, years
<10	31.9	26.9	22.9	21.0	17.3	15.1	15.2	12.9	9.8	8.0	6.6	16.0	13.3	11.7	11.7
10–12	36.9	41.2	45.3	45.2	44.1	43.1	40.2	55.7	55.9	55.7	52.0	51.8	56.5	58.9	58.0
>12	28.8	29.8	29.8	31.9	38.6	41.8	44.5	30.2	33.1	34.8	38.4	30.2	29.3	28.4	29.2
Missing	2.4	2.1	2.0	1.9				1.2	1.2	1.5	3.1	2.0	0.8	1.0	1.0

Maternal age, years
<20	4.3	2.9	2.3	1.8	2.9	2.7	2.7	6.1	4.7	3.4	2.7	3.8	3.0	2.5	2.0
20–34	88.7	88.6	87.3	85.0	83.5	83.4	80.2	86.5	87.0	85.7	84.1	85.6	85.6	85.2	83.0
≥35	7.0	8.5	10.3	13.2	13.6	13.9	17.2	7.4	8.3	10.9	13.3	10.6	11.4	12.4	15.1

Parity
0	48.5	47.0	44.4	42.9	39.8	40.1	40.3	42.6	43.8	41.8	40.5	41.0	42.7	41.4	42.3
1+	51.5	53.0	55.6	57.1	59.8	59.8	59.6	56.3	54.9	57.2	58.3	59.1	57.3	58.7	57.7
Missing					0.4	0.2	0.1	1.1	1.2	1.0	1.3

Mother born outside country
No	94.3	92.7	90.6	87.4	97.0	95.6	93.6	94.7	92.8	90.7	87.6	87.9	87.5	84.4	82.6
Yes	5.7	7.3	9.5	12.6	3.0	4.4	6.4	5.4	7.2	9.3	12.4	12.1	12.5	15.6	17.5

All (n)	249931	288369	324816	319772	241597	312156	278887	229880	251971	263202	273519	452842	538540	556279	426473

Figures in the table are percentages.
↵* Weighted numbers.
↵† The period 1986–90 in Finland refers to 1987–90. No data were available before 1987.
Due to rounding the numbers do not consistently sum up to 100%.