Descriptive characteristics of the main cohort and the subcohort with detailed delivery data, stratified by mode of delivery
|
| Main cohort | Subcohort with detailed delivery data | |||
| Vaginal delivery | Any caesarean section | Vaginal delivery | Elective caesarean section | Non-elective caesarean section | |
| Total no of observations, (%) | 522 853 (90.3) | 56 371 (9.7) | 169 666 (91.4) | 7 740 (4.2) | 8 280 (4.5) |
| Age at conscription (years), median (IQR) | 18.3 (18.1–18.5) | 18.3 (18.1–18.5) | 18.3 (18.1–18.5) | 18.3 (18.1–18.5) | 18.3 (18.1–18.5) |
| Birth weight (g), mean (SD) | 3 600.8 (516.0) | 3 371.9 (677.1) | 3 617.3 (512.8) | 3 410.3 (575.0) | 3 309.1 (813.7) |
| Fetal growth, no (%) | |||||
| Small for gestational age (<10th %ile) | 48 141 (9.2) | 7 981 (14.2) | 12 569 (7.4) | 725 (9.4) | 1 271 (15.4) |
| Appropriate for gestational age | 421 966 (80.7) | 42 263 (75.0) | 138 217 (81.5) | 5 997 (77.5) | 6 061 (73.2) |
| Large for gestational age (>90th %ile) | 52 746 (10.1) | 6 127 (10.9) | 18 880 (11.1) | 1 018 (13.2) | 948 (11.4) |
| Gestational age (weeks), mean (SD) | 39.7 (1.7) | 38.7 (2.3) | 39.5 (1.6) | 38.1 (1.5) | 38.5 (3.0) |
| Gestational periods, no (%) | |||||
| Extremely preterm (<28 wGA) | 170 (<1) | 54 (0.1) | 51 (<1) | <10 | 29 (0.4) |
| Very preterm (28–31 wGA) | 1 027 (0.2) | 809 (1.4) | 248 (0.1) | 42 (0.5) | 277 (3.3) |
| Moderate to late preterm (32–36 wGA) | 18 953 (3.6) | 6 066 (10.8) | 6 594 (3.9) | 506 (6.5) | 1 424 (17.2) |
| Early term (37–38 wGA) | 77 017 (14.7) | 16 996 (30.2) | 28 678 (16.9) | 4 723 (61.0) | 1 589 (19.2) |
| Full term (39–40 wGA) | 263 153 (50.3) | 21 725 (38.5) | 89 969 (53.0) | 2 116 (27.3) | 2 672 (32.3) |
| Late term (41 wGA) | 104 998 (20.1) | 5 798 (10.3) | 31 511 (18.6) | 209 (2.7) | 1 337 (16.1) |
| Post-term (≥42 wGA) | 57 535 (11.0) | 4 923 (8.7) | 12 615 (7.4) | 143 (1.8) | 952 (11.5) |
| Modified Robson classification, no (%) | |||||
| 1+2 | 203 564 (38.9) | 22 112 (39.2) | 64 605 (38.1) | 1 755 (22.7) | 3 912 (47.2) |
| 3+4 | 287 984 (55.1) | 16 654 (29.5) | 94 088 (55.5) | 2 620 (33.9) | 1 791 (21.6) |
| 5 | 4 324 (0.8) | 5 979 (10.6) | 2 718 (1.6) | 2 068 (26.7) | 440 (5.3) |
| 6+7 | 5 803 (1.1) | 5 366 (9.5) | 985 (0.6) | 781 (10.1) | 601 (7.3) |
| 9+10 | 21 178 (4.1) | 6 260 (11.1) | 7 270 (4.3) | 516 (6.7) | 1 536 (18.6) |
| Parity, median (IQR) | 2.0 (1.0–2.0) | 2.0 (1.0–2.0) | 2.0 (1.0–2.0) | 2.0 (1.0–3.0) | 1.0 (1.0–2.0) |
| Maternal age at birth (years), mean (SD) | 27.5 (4.9) | 29.0 (5.6) | 28.3 (5.0) | 30.5 (5.4) | 28.7 (5.4) |
| Categories of maternal age, no (%) | |||||
| <20 years | 24 507 (4.7) | 1 960 (3.5) | 5024 (3.0) | 98 (1.3) | 235 (2.8) |
| 20–24 years | 147 504 (28.2) | 12 554 (22.3) | 41 037 (24.2) | 1 133 (14.6) | 1 972 (23.8) |
| 25–29 years | 198 443 (38.0) | 19 087 (33.9) | 63 567 (37.5) | 2 538 (32.8) | 2 977 (36.0) |
| 30–34 years | 113 144 (21.6) | 13 936 (24.7) | 42 281 (24.9) | 2 260 (29.2) | 1 968 (23.8) |
| ≥35 years | 39 255 (7.5) | 8 834 (15.7) | 17 757 (10.5) | 1 711 (22.1) | 1 128 (13.6) |
| Maternal diabetes mellitus, no (%) | 1 578 (0.3) | 987 (1.8) | 871 (0.5) | 173 (2.2) | 95 (1.1) |
| Maternal hypertension, no (%) | 449 (0.1) | 165 (0.3) | 330 (0.2) | 44 (0.6) | 48 (0.6) |
| Pre-eclampsia, no (%) | 2 437 (0.5) | 1 046 (1.9) | 2 046 (1.2) | 212 (2.7) | 505 (6.1) |
| Highest parental education, no (%) | |||||
| Primary education | 67 918 (13.0) | 7 415 (13.2) | 17 184 (10.1) | 810 (10.5) | 890 (10.7) |
| Secondary education | 262 833 (50.3) | 27 155 (48.2) | 86 717 (51.1) | 3 721 (48.1) | 4 257 (51.4) |
| University education | 192 102 (36.7) | 21 801 (38.7) | 65 765 (38.8) | 3 209 (41.5) | 3 133 (37.8) |
| Familial disposable income, no (%) | |||||
| Quintile 1 | 60 174 (11.5) | 6 963 (12.4) | 35 421 (20.9) | 1 445 (18.7) | 1 829 (22.1) |
| Quintile 2 | 104 135 (19.9) | 10 709 (19.0) | 42 007 (24.8) | 1 709 (22.1) | 2 056 (24.8) |
| Quintile 3 | 124 926 (23.9) | 12 251 (21.7) | 36 535 (21.5) | 1 647 (21.3) | 1 814 (21.9) |
| Quintile 4 | 120 651 (23.1) | 12 696 (22.5) | 30 646 (18.1) | 1 481 (19.1) | 1 394 (16.8) |
| Quintile 5 | 112 967 (21.6) | 13 752 (24.4) | 25 057 (14.8) | 1 458 (18.8) | 1 187 (14.3) |
| Parent(s) born in Sweden, no (%) | |||||
| Both parents | 452 640 (86.6) | 48 063 (85.3) | 145 352 (85.7) | 6 571 (84.9) | 6 983 (84.3) |
| One parent | 49 343 (9.4) | 5 854 (10.4) | 16 503 (9.7) | 837 (10.8) | 854 (10.3) |
| Neither parent | 20 870 (4.0) | 2 454 (4.4) | 7 811 (4.6) | 332 (4.3) | 443 (5.4) |
| Parental labour market position, no (%) | |||||
| Others | 19 521 (3.7) | 2 283 (4.0) | 7 417 (4.4) | 348 (4.5) | 368 (4.4) |
| Unskilled workers | 93 311 (17.8) | 9 386 (16.7) | 26 995 (15.9) | 1 164 (15.0) | 1 374 (16.6) |
| Skilled workers | 101 566 (19.4) | 10 170 (18.0) | 32 423 (19.1) | 1 328 (17.2) | 1 576 (19.0) |
| Self-employed and farmers | 32 069 (6.1) | 3 586 (6.4) | 10 090 (5.9) | 440 (5.7) | 484 (5.8) |
| Non-manual workers at lower level | 78 417 (15.0) | 8 481 (15.0) | 24 577 (14.5) | 1 141 (14.7) | 1 256 (15.2) |
| Non-manual workers at intermediate level | 126 455 (24.2) | 13 620 (24.2) | 40 956 (24.1) | 1 872 (24.2) | 1 932 (23.3) |
| Non-manual workers at higher level | 71 514 (13.7) | 8 845 (15.7) | 27 208 (16.0) | 1 447 (18.7) | 1 290 (15.6) |
%ile, percentile; IQR, interquartile range; No., number of observations; SD, standard deviation; wGA, weeks of gestational age.