Supplemental Table 2.
Characteristics of births in Norway by year, 2014 to 2020
| Characteristics | All |
2014 |
2015 |
2016 |
2017 |
2018 |
2019 |
2020 |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | (%) | n | (%) | n | (%) | n | (%) | n | (%) | n | (%) | n | (%) | n | (%) | |
| All births | 392,586 | 58,548 | 58,417 | 58,563 | 56,123 | 54,734 | 54,053 | 52,148 | ||||||||
| Gestational age (wk) | ||||||||||||||||
| Extremely preterm <28 | 1449 | (0.4) | 250 | (0.4) | 232 | (0.4) | 209 | (0.4) | 203 | (0.4) | 195 | (0.4) | 194 | (0.4) | 166 | (0.3) |
| Very preterm 28–<32 |
2123 | (0.5) | 324 | (0.6) | 316 | (0.5) | 339 | (0.6) | 281 | (0.5) | 268 | (0.5) | 311 | (0.6) | 284 | (0.5) |
| Moderate or late preterm 32–<37 | 18,256 | (4.7) | 2685 | (4.6) | 2750 | (4.7) | 2789 | (4.8) | 2587 | (4.6) | 2539 | (4.6) | 2506 | (4.6) | 2400 | (4.6) |
| Term 37–<42 | 354,821 | (90.4) | 53,200 | (90.9) | 52,848 | (90.5) | 52,873 | (90.3) | 50,448 | (89.9) | 49,397 | (90.2) | 48,665 | (90.0) | 47,390 | (90.9) |
| Postterm ≥42 | 15,937 | (4.1) | 2089 | (3.6) | 2271 | (3.9) | 2353 | (4.0) | 2604 | (4.6) | 2335 | (4.3) | 2377 | (4.4) | 1908 | (3.7) |
| Maternal age | ||||||||||||||||
| <20 | 3710 | (0.9) | 808 | (1.4) | 741 | (1.3) | 659 | (1.1) | 489 | (0.9) | 414 | (0.8) | 349 | (0.6) | 250 | (0.5) |
| 20–24 | 41,279 | (10.5) | 7474 | (12.8) | 7097 | (12.1) | 6618 | (11.3) | 5790 | (10.3) | 5395 | (9.9) | 4755 | (8.8) | 4150 | (8.0) |
| 25–29 | 126,280 | (32.2) | 18,765 | (32.1) | 19,179 | (32.8) | 19,224 | (32.8) | 18,553 | (33.1) | 17,641 | (32.2) | 16,896 | (31.3) | 16,022 | (30.7) |
| 30–34 | 139,841 | (35.6) | 19,852 | (33.9) | 19,593 | (33.5) | 20,243 | (34.6) | 19,820 | (35.3) | 19,999 | (36.5) | 20,254 | (37.5) | 20,080 | (38.5) |
| 35–39 | 66,785 | (17.0) | 9558 | (16.3) | 9733 | (16.7) | 9666 | (16.5) | 9356 | (16.7) | 9295 | (17.0) | 9623 | (17.8) | 9554 | (18.3) |
| ≥40 | 14,690 | (3.7) | 2091 | (3.6) | 2074 | (3.6) | 2152 | (3.7) | 2115 | (3.8) | 1990 | (3.6) | 2176 | (4.0) | 2092 | (4.0) |
| Missing | 1 | 1 | ||||||||||||||
| Parity | ||||||||||||||||
| 0 | 166,742 | (42.5) | 24,754 | (42.3) | 24,920 | (42.7) | 24,901 | (42.5) | 23,624 | (42.1) | 23,168 | (42.3) | 22,999 | (42.5) | 22,376 | (42.9) |
| ≥1 | 225,844 | (57.5) | 33,794 | (57.7) | 33,497 | (57.3) | 33,662 | (57.5) | 32,499 | (57.9) | 31,566 | (57.7) | 31,054 | (57.5) | 29,772 | (57.1) |
| Missing | ||||||||||||||||
| Multiple birth | ||||||||||||||||
| Yes | 6107 | (1.6) | 937 | (1.6) | 982 | (1.7) | 935 | (1.6) | 898 | (1.6) | 821 | (1.5) | 826 | (1.5) | 708 | (1.4) |
| No | 386,479 | (98.4) | 57,611 | (98.4) | 57,435 | (98.3) | 57,628 | (98.4) | 55,225 | (98.4) | 52,913 | (96.7) | 53,227 | (98.5) | 51,440 | (98.6) |
| Country of birth | ||||||||||||||||
| Norway | 275,365 | (70.1) | 41,835 | (71.5) | 41,230 | (70.6) | 41,124 | (70.2) | 38,758 | (69.1) | 37,862 | (69.2) | 37,688 | (69.7) | 36,868 | (70.7) |
| Other Scandinavia | 8228 | (2.1) | 1213 | (2.1) | 1210 | (2.1) | 1243 | (2.1) | 1154 | (2.1) | 1155 | (2.1) | 1179 | (2.2) | 1074 | (2.1) |
| Outside Scandinavia | 107,318 | (27.3) | 15,187 | (25.9) | 15,703 | (26.9) | 15,957 | (27.2) | 15,953 | (28.4) | 15,526 | (28.4) | 14,982 | (27.7) | 14,010 | (26.9) |
| Missing | 1675 | (0.4) | 313 | (0.5) | 274 | (0.5) | 239 | (0.4) | 258 | (0.5) | 191 | (0.3) | 204 | (0.4) | 196 | (0.4) |
| Maternal education status (y) | ||||||||||||||||
| ≤9 | 58,273 | (14.8) | 8910 | (15.2) | 9037 | (15.5) | 8911 | (15.2) | 8477 | (15.1) | 8175 | (14.9) | 7773 | (14.4) | 6990 | (13.4) |
| 10–12 | 85,421 | (21.8) | 13,806 | (23.6) | 13,507 | (23.1) | 13,095 | (22.4) | 12,109 | (21.6) | 11,404 | (20.8) | 11,118 | (20.6) | 10,382 | (19.9) |
| >12 | 218,689 | (55.7) | 32,129 | (54.9) | 32,045 | (54.9) | 32,287 | (55.1) | 31,039 | (55.3) | 30,441 | (55.6) | 30,620 | (56.6) | 30,128 | (57.8) |
| Missing | 30,203 | (7.7) | 3703 | (6.3) | 3828 | (6.6) | 4270 | (7.3) | 4498 | (8.0) | 4714 | (8.6) | 4542 | (8.4) | 4648 | (8.9) |
| Season of conceptiona | ||||||||||||||||
| Winter | 90,360 | (23.0) | 13,352 | (22.8) | 13,492 | (23.1) | 13,304 | (22.7) | 12,928 | (23.0) | 12,648 | (23.1) | 12,580 | (23.3) | 12,056 | (23.1) |
| Spring | 92,381 | (23.5) | 13,979 | (23.9) | 13,628 | (23.3) | 13,772 | (23.5) | 13,198 | (23.5) | 12,837 | (23.5) | 12,789 | (23.7) | 12,178 | (23.4) |
| Summer | 102,690 | (26.2) | 15,405 | (26.3) | 15,081 | (25.8) | 15,641 | (26.7) | 14,734 | (26.3) | 14,271 | (26.1) | 13,946 | (25.8) | 13,612 | (26.1) |
| Fall | 107,155 | (27.3) | 15,812 | (27.0) | 16,216 | (27.8) | 15,846 | (27.1) | 15,263 | (27.2) | 14,978 | (27.4) | 14,738 | (27.3) | 14,302 | (27.4) |
| BMI (kg/m2) | ||||||||||||||||
| <18.5 | 12,941 | (3.3) | 1777 | (3.0) | 1858 | (3.2) | 1973 | (3.4) | 1984 | (3.5) | 1884 | (3.4) | 1821 | (3.4) | 1644 | (3.2) |
| 18.5–<25 | 200,623 | (51.1) | 26,170 | (44.7) | 27,091 | (46.4) | 29,939 | (51.1) | 29,713 | (52.9) | 29,851 | (54.5) | 29,524 | (54.6) | 28,335 | (54.3) |
| 25–<30 | 73,321 | (18.7) | 9008 | (15.4) | 9385 | (16.1) | 10,553 | (18.0) | 10,653 | (19.0) | 11,121 | (20.3) | 11,306 | (20.9) | 11,295 | (21.7) |
| ≥30 | 41,315 | (10.5) | 5047 | (8.6) | 5060 | (8.7) | 5665 | (9.7) | 5901 | (10.5) | 6230 | (11.4) | 6657 | (12.3) | 6755 | (13.0) |
| Missing | 64,386 | (16.4) | 16,546 | (28.3) | 15,023 | (25.7) | 10,433 | (17.8) | 7872 | (14.0) | 5648 | (10.3) | 5746 | (10.6) | 4119 | (7.9) |
| Smoking in early pregnancy | ||||||||||||||||
| No | 342,517 | (87.2) | 48,487 | (82.8) | 50,595 | (86.6) | 51,729 | (88.3) | 49,308 | (87.9) | 48,488 | (88.6) | 48,104 | (89.0) | 46,006 | (88.2) |
| Yes | 15,199 | (3.9) | 3678 | (6.3) | 2941 | (5.0) | 2530 | (4.3) | 1993 | (3.6) | 1665 | (3.0) | 1301 | (2.4) | 1091 | (2.1) |
| Missing | 34,870 | (8.9) | 6383 | (10.9) | 4881 | (8.4) | 4304 | (7.3) | 4822 | (8.6) | 4781 | (8.7) | 4648 | (8.6) | 5051 | (9.7) |
BMI, body mass index.
Oakley et al. Preterm birth and COVID-19 mitigation measures in Scandinavia. Am J Obstet Gynecol 2022.
a
Winter (December–February); Spring (March–May); Summer (June–August); Fall (September–November).