Table 1 Characteristics of the study population (singleton births from 1980 to 2010 in WA) and their mothers by maternal country of birth group
|  | ANI (n = 509,589) | AI (n = 44,820) | FB-LIC (n = 4458) | FB-LMIC (n = 33,315) | FB-UMIC (n = 31,254) | FB-HIC (n = 146,259) | Total (n = 769,695) |
|---|---|---|---|---|---|---|---|
Gender | |||||||
 Female | 248,116 (48.7) | 21,868 (48.8) | 2175 (48.8) | 16,076 (48.3) | 15,038 (48.1) | 71,344 (48.8) | 374,617 (48.7) |
 Male | 261,455 (51.3) | 22,943 (51.2) | 2282 (51.2) | 17,238 (51.7) | 16,212 (51.9) | 74,909 (51.2) | 395,039 (51.3) |
 Total | 509,571 (100) | 44,811 (100) | 4457 (100) | 33,314 (100) | 31,250 (100) | 146,253 (100) | 769,656 (100) |
Pearson chi2 (5) 7.1953, Pr = 0.207 | |||||||
Maternal age | |||||||
 < 20 years | 28,763 (5.6) | 12,179 (27.2) | 118 (2.7) | 629 (1.9) | 675 (2.2) | 4587 (3.1) | 46,951 (6.1) |
 20–24 years | 107,752 (21.2) | 15,375 (34.3) | 777 (17.4) | 4831 (14.5) | 4331 (13.9) | 23,496 (16.1) | 156,562 (20.3) |
 25–29 years | 175,640 (34.5) | 10,012 (22.3) | 1438 (32.3) | 11,006 (33.0) | 9505 (30.4) | 45,334 (31.0) | 252,935 (32.9) |
 30–34 years | 137,957 (27.1) | 5032 (11.2) | 1300 (29.2) | 10,661 (32.0) | 10,360 (33.2) | 46,067 (31.5) | 211,377 (27.5) |
 35–39 years | 51,455 (10.1) | 1877 (4.2) | 682 (15.3) | 5155 (15.5) | 5276 (16.9) | 22,379 (15.3) | 86,824 (11.3) |
 > 39 years | 8009 (1.6) | 345 (0.8) | 143 (3.2) | 1033 (3.1) | 1106 (3.5) | 4395 (3.0) | 15,031 (2.0) |
 Total | 509,576 (100) | 44,820 (100) | 4458 (100) | 33,315 (100) | 31,253 (100) | 146,258 (100) | 769,680 (100) |
Pearson chi2 (25) 6.0 × 10+ 4 Pr < 0.001 | |||||||
Marital status | |||||||
 Never married | 43,661 (8.6) | 15,482 (34.5) | 239 (5.4) | 1318 (4) | 878 (2.8) | 9110 (6.2) | 70,688 (9.2) |
 Widowed | 335 (0.07) | 78 (0.2) | 10 (0.4) | 50 (0.2) | 15 (0.05) | 88 (0.3) | 576 (0.07) |
 Divorced | 1812 (0.4) | 95 (0.2) | 18 (0.4) | 91 (0.3) | 85 (0.3) | 618 (0.4) | 2719 (0.4) |
 Separated | 3620 (0.7) | 682 1.5) | 84 (1.9) | 251 (0.8) | 180 (0.6) | 1004 (0.7) | 5821 (0.8) |
 Married | 459,242 (90.1) | 28,167 (62.8) | 4089 (91.7) | 31,491 (94.5) | 29,994 (96.0) | 135,159 (92.4) | 688,142 (89.4) |
 Unknown | 919 (0.2) | 316 (0.7) | 18 (0.4) | 114 (0.3) | 102 (0.3) | 280 (0.2) | 1749 (0.2) |
 Total | 509,589 (100) | 44,820 (100) | 4458 (100) | 33,315 (100) | 31,254 (100) | 146,259 (100) | 769,695 (100) |
Pearson chi2 (25) 4.1 × 10+ 4 Pr < 0.001 | |||||||
SEIFA score | |||||||
 0–10 | 44,509 (9.9) | 12,552 (35) | 535 (12.9) | 4071 (13.3) | 2582 (8.9) | 10,895 (8.2) | 75,144 (11) |
 11–25 | 74,190 (16.5) | 8691 (24.3) | 762 (18.5) | 5000 (16.3) | 3933 (13.6) | 19,911 (15) | 112,487 (16.5) |
 26–50 | 116,710 (26) | 8,141 (22.7) | 1169 (28.4) | 7965 (26) | 6912 (23.9) | 33,416 (25.1) | 174,313 (25.6) |
 51–75 | 113, 336 (25.2) | 4749 (13.3) | 868 (21.1) | 7292 (23.8) | 7535 (26) | 34,856 (26.2) | 168,636 (24.7) |
 76–90 | 63,480 (14.1) | 1375 (3.8) | 490 (11.9) | 3881 (12.7) | 4802 (16.6) | 21,121 (15.9) | 95,149 (13.9) |
 > 90 | 37,467 (8.3) | 321 (0.9) | 295 (7.2) | 2450 (8) | 3174 (11) | 12,901 (9.7) | 56,608 (8.3) |
 Total | 449,692 (100) | 35,829 (100) | 4119 (100) | 30,659 (100) | 28,938 (100) | 133,100 (100) | 682,337 (100) |
Pearson chi2 (25) 3.1 × 10+ 4 Pr < 0.001 | |||||||
Parity | |||||||
 0 | 210,158 (41.5) | 13,122 (30.7) | 1360 (31.8) | 13,932 (42.2) | 12,725 (41) | 57,523 (39.6) | 308,820 (40.5) |
 1 | 171,955 (40) | 10,392 (24.3) | 1267 (29.6) | 11,375 (34.4) | 10,998 (35.4) | 50,008 (34.5) | 255,995 (33.6) |
 2 | 83,577 (16.5) | 8097 (19) | 763 (17.8) | 4999 (15.1) | 4908 (15.8) | 24,633 (17) | 126,977 (16.7) |
 3 | 28,546 (5.6) | 5585 (11.1) | 467 (11) | 1830 (5.5) | 1611 (5.2) | 8978 (6.25) | 47,017 (6.2) |
 4 | 8980 (1.8) | 3466 (8.1) | 269 (6.3) | 667 (2.0) | 573 (2) | 2955 (2) | 16,910 (2.2) |
 5 & more | 3044 (0.6) | 2034 (4.8) | 157 (3.7) | 249 (0.8) | 218 (0.7) | 1057 (0.7) | 6759 (0.9) |
 Total | 506,260 (100) | 42,696 (100) | 4283 (100) | 33,052 (100) | 31,033 (100) | 145,154 (100) | 762,478 (100) |
Pearson chi2 (25) 2.2 × 10+ 4 Pr < 0.001 | |||||||
Smoking | |||||||
 Yes | 42,866 (18.3) | 10,892 (50.7) | 58 (1.9) | 507 (2.8) | 1034 (5.9) | 8543 (15.2) | 63,900 (18.2) |
 No | 191,678 (81.7) | 10,603 (49.3) | 3023 (98.1) | 17,660 (97.2) | 16,617 (94.4) | 47,642 (84.8) | 287,223 (81.8) |
 Total | 234,544 (100) | 21,495 (100) | 3081 (100) | 18,167 (100) | 17,651 (100) | 56,185 (100) | 351,123 (100) |
Pearson chi2 (25) 2.1 × 10+ 4 Pr < 0.001 | |||||||