Table 1 Maternal characteristics by migrant and non-migrant women giving birth in Norway, 1990–2013a
| Â | Primiparous women | Multiparous women | ||
|---|---|---|---|---|
Migrant | Non-migrant | Migrant | Non-migrant | |
(n = 80,119) | (n = 468,983) | (n = 115,606) | (n = 667,654) | |
n (%) | n (%) | n (%) | n (%) | |
Age (years) | ||||
 < 25 | 23,983 (29.9) | 163,323 (34.8) | 12,629 (10.9) | 63,940 (9.6) |
 25–29 | 29,379 (36.7) | 180,607 (38.5) | 34,481 (29.8) | 212,756 (31.9) |
 30–34 | 19,392 (24.2) | 93,888 (20.0) | 40,957 (35.4) | 254,405 (38.1) |
 35–39 | 6338 (7.9) | 26,923 (5.7) | 22,501 (19.5) | 116,858 (17.5) |
 ≥40 | 1027 (1.3) | 4242 (0.9) | 5038 (4.4) | 19,695 (2.9) |
Single status b | 6652 (8.3) | 58,059 (12.4) | 8864 (7.7) | 34,807 (5.2) |
Consanguinity, second cousin or closer | 2082 (2.6) | 594 (0.1) | 4467 (3.9) | 1167 (0.2) |
Mother’s education | ||||
 No education | 856 (1.1) | 4 (0.0) | 3541 (3.1) | 41 (0.0) |
 Primary education | 15,538 (19.4) | 96,802 (20.6) | 30,960 (26.8) | 147,867 (22.1) |
 Secondary school | 15,897 (19.8) | 180,494 (38.5) | 23,811 (20.6) | 255,916 (38.3) |
 University/college | 26,002 (32.5) | 190,883 (40.7) | 29,978 (25.9) | 262,404 (39.3) |
 Missing | 21,826 (27.2) | 800 (0.2) | 27,316 (23.6) | 1426 (0.2) |
Mother’s incomec | ||||
 ≤25 percentile | 18,250 (22.8) | 98,494 (21.0) | 26,044 (22.5) | 146,471 (21.9) |
 25–50 percentile | 12,391 (15.5) | 98,342 (21.0) | 16,943 (14.7) | 163,221 (24.4) |
 50–75 percentile | 8793 (11.0) | 121,703 (26.0) | 10,600 (9.2) | 148,630 (22.3) |
 ≥75 percentile | 9898 (12.4) | 122,450 (26.1) | 11,149 (9.6) | 142,284 (21.3) |
 Missing | 30,787 (38.4) | 27,994 (6.0) | 50,870 (44.0) | 67,048 (10.0) |
Chronic hypertension | 245 (0.3) | 2043 (0.4) | 518 (0.4) | 3506 (0.5) |
Pre-eclampsia/eclampsia | 2971 (3.7) | 25,391 (5.4) | 2252 (1.9) | 15,988 (2.4) |
Pre-pregnancy diabetes d | ||||
 Type 1 | 152 (0.2) | 1616 (0.3) | 314 (0.3) | 2057 (0.3) |
 Type 2 | 157 (0.2) | 402 (0.1) | 476 (0.4) | 746 (0.1) |
Maternal overweight (BMI ≥ 25) e | 3501 (10.4) | 17,673 (16.1) | 7454 (16.5) | 26,520 (17.7) |
 Not overweight | 12,622 (37.5) | 33,785 (30.8) | 12,887 (28.5) | 42,331 (28.2) |
 Missing | 17,548 (52.1) | 58,371 (53.1) | 24,952 (55.1) | 81,359 (54.2) |
Smoking before pregnancy e | 3133 (5.0) | 21,990 (7.9) | 3014 (3.4) | 22,603 (5.7) |
 Non-smoker | 21,343 (33.7) | 67,540 (24.4) | 29,655 (33.3) | 104,803 (26.6) |
 Missing | 38,807 (61.3) | 187,681 (67.7) | 56,414 (63.3) | 267,054 (67.7) |
Former stillbirths | Â | Â | 2639 (2.3) | 9336 (1.4) |
Parity | ||||
 0 | 80,119 (100.0) | 468,983 (100.0) |  |  |
 1 |  |  | 64,191 (55.5) | 411,085 (61.6) |
 2 |  |  | 29,859 (25.8) | 189,681 (28.4) |
 3 |  |  | 12,127 (10.5) | 48,959 (7.3) |
 4 |  |  | 5043 (4.4) | 11,999 (1.8) |
 ≥5 |  |  | 4386 (3.8) | 5930 (0.9) |
Gestational age (weeks) | ||||
 Very preterm (22–27 weeks) | 403 (0.5) | 2247 (0.5) | 591 (0.5) | 2576 (0.4) |
 Moderately preterm (28–36 weeks) | 4951 (6.2) | 30,779 (6.6) | 6481 (5.6) | 31,701 (4.7) |
 Term (37–41 weeks) | 66,354 (82.8) | 367,439 (78.3) | 98,033 (84.8) | 552,939 (82.8) |
 Post term (≥ 42 weeks) | 6454 (8.1) | 49,734 (10.6) | 6969 (6.0) | 52,688 (7.9) |
 Missing | 1957 (2.4) | 18,784 (4.0) | 3532 (3.1) | 27,750 (4.2) |