Table 2.
Characteristics of included births from 2014 to 2020 in Norway, Sweden, and Denmark
| Characteristics | Norway |
Sweden |
Denmark |
|||
|---|---|---|---|---|---|---|
| n | (%) | n | (%) | n | (%) | |
| All births | 392,586 | 713,121 | 413,814 | |||
| Gestational age (wk) | ||||||
| Extremely preterm <28 | 1449 | (0.4) | 2670 | (0.4) | 1620 | (0.4) |
| Very preterm 28–<32 | 2123 | (0.5) | 3912 | (0.5) | 2393 | (0.6) |
| Moderate/late preterm 32–<37 | 18,256 | (4.7) | 33,264 | (4.7) | 19,411 | (4.7) |
| Term 37–<42 | 354,821 | (90.4) | 636,182 | (89.2) | 381,218 | (92.1) |
| Postterm ≥42 | 15,937 | (4.1) | 36,113 | (5.1) | 9172 | (2.2) |
| Maternal age | ||||||
| <20 | 3710 | (0.9) | 7266 | (1.0) | 3296 | (0.8) |
| 20–24 | 41,279 | (10.5) | 75,668 | (10.6) | 41,652 | (10.1) |
| 25–29 | 126,280 | (32.2) | 223,444 | (31.3) | 138,920 | (33.6) |
| 30–34 | 139,841 | (35.6) | 246,949 | (34.6) | 144,304 | (34.9) |
| 35–39 | 66,785 | (17.0) | 128,099 | (18.0) | 69,390 | (16.8) |
| ≥40 | 14,690 | (3.7) | 31,484 | (4.4) | 16,252 | (3.9) |
| Missing | 1 | (0.0) | 211 | (0.0) | ||
| Parity | ||||||
| 0 | 166,742 | (42.5) | 306,085 | (42.9) | 190,650 | (46.1) |
| ≥1 | 225,844 | (57.5) | 402,892 | (56.5) | 223,120 | (53.9) |
| Missing | 4144 | (0.6) | 44 | (0.0) | ||
| Multiple birth | ||||||
| Yes | 6107 | (1.6) | 10,072 | (1.4) | 6768 | (1.6) |
| No | 386,479 | (98.4) | 703,049 | (98.6) | 407,046 | (98.4) |
| Season of conceptiona | ||||||
| Winter | 90,360 | (23.0) | 186,013 | (26.1) | 105,919 | (25.6) |
| Spring | 92,381 | (23.5) | 189,348 | (26.6) | 97,751 | (23.6) |
| Summer | 102,690 | (26.2) | 170,177 | (23.9) | 100,506 | (24.3) |
| Fall | 107,155 | (27.3) | 167,583 | (23.5) | 109,638 | (26.5) |
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).