Table 1.
Participant characteristics by mode of birth
| All (n=37 417) | Mode of birth | ||||||
| Only spontaneous births (n=23 608) | Instrumental vaginal birth, ever (n=5003) | Only c-sections (n=3244) | Spontaneous VBAC (n=2 038) | Instrumental VBAC (n=457) | C-section after vaginal birth (n=3 067) | ||
| Age at first birth, n (%) | |||||||
| <25 | 7140 (19) | 4864 (21) | 775 (15) | 363 (11) | 356 (17) | 75 (16) | 707 (23) |
| 25–29 | 19 839 (53) | 12 758 (54) | 2656 (53) | 1433 (44) | 1144 (56) | 233 (51) | 1615 (53) |
| 30–34 | 8614 (23) | 5063 (21) | 1280 (26) | 1024 (32) | 465 (23) | 125 (27) | 657 (21) |
| ≥35 | 1824 (5) | 923 (4) | 292 (6) | 424 (13) | 73 (4) | 24 (5) | 88 (3) |
| Socio-occupational status, n (%)* | |||||||
| Low | 2233 (6) | 1393 (6) | 265 (6) | 202 (7) | 123 (6) | 28 (7) | 222 (8) |
| Middle | 11 832 (34) | 7444 (34) | 1562 (33) | 1056 (35) | 656 (34) | 133 (31) | 981 (34) |
| High | 21 059 (60) | 13 318 (60) | 2875 (61) | 1779 (59) | 1133 (59) | 269 (63) | 1685 (58) |
| Missing | 2293 | 1453 | 301 | 207 | 126 | 27 | 179 |
| Prepregnant BMI, n (%)* | |||||||
| <18.5 | 1417 (4) | 906 (4) | 196 (4) | 87 (3) | 82 (4) | 26 (6) | 120 (4) |
| 18.5–24.9 | 24 554 (71) | 15 991 (73) | 3275 (70) | 1843 (62) | 1286 (68) | 268 (63) | 1891 (66) |
| 25.0–29.9 | 6405 (18) | 3748 (17) | 899 (19) | 697 (23) | 369 (20) | 93 (22) | 599 (21) |
| ≥30.0 | 2321 (7) | 1249 (6) | 278 (6) | 355 (12) | 150 (8) | 37 (9) | 252 (9) |
| Missing | 2720 | 1714 | 355 | 262 | 151 | 33 | 205 |
| Exercise in pregnancy, min/week, n (%)* | |||||||
| None | 21 156 (60) | 13 137 (59) | 2881 (61) | 1888 (62) | 1149 (60) | 274 (64) | 1827 (63) |
| 1–180 | 11 184 (32) | 7222 (33) | 1475 (31) | 900 (30) | 615 (32) | 122 (28) | 850 (29) |
| >180 | 2826 (8) | 1825 (8) | 348 (7) | 255 (8) | 148 (8) | 33 (8) | 217 (8) |
| Missing | 2251 | 1424 | 299 | 201 | 126 | 28 | 173 |
| Smoking in pregnancy, n (%)* | |||||||
| No smoking | 28 295 (80) | 17 973 (80) | 3774 (80) | 2372 (77) | 1545 (80) | 352 (81) | 2279 (78) |
| Smoking cessation | 3099 (9) | 1892 (8) | 425 (9) | 318 (10) | 173 (9) | 28 (6) | 263 (9) |
| Smoking | 4062 (11) | 2489 (11) | 536 (11) | 378 (12) | 222 (11) | 54 (12) | 383 (13) |
| Missing | 1961 | 1254 | 268 | 176 | 98 | 23 | 142 |
| Self-assessed health, n (%)* | |||||||
| Very good | 19 750 (56) | 12 630 (57) | 2642 (56) | 1631 (53) | 1079 (56) | 228 (53) | 1540 (53) |
| Normal | 14 578 (41) | 9056 (41) | 1963 (42) | 1319 (43) | 798 (41) | 195 (45) | 1247 (43) |
| Not so good | 970 (3) | 576 (3) | 116 (2) | 109 (4) | 47 (2) | 11 (3) | 111 (4) |
| Missing | 2 119 | 1346 | 282 | 185 | 114 | 23 | 169 |
| Presence of disease, n (%)*† | |||||||
| No | 20 305 (58) | 13 105 (59) | 2774 (59) | 1577 (52) | 1095 (57) | 251 (58) | 1503 (52) |
| Yes | 14 855 (42) | 9070 (41) | 1932 (41) | 1468 (48) | 820 (43) | 182 (42) | 1383 (48) |
| Missing | 2257 | 1433 | 297 | 199 | 123 | 24 | 181 |
*Percentage of non-missing values.
†Diseases that, according to the women, had been confirmed by a physician, including hypertensive disorders, diseases of the heart, thyroid or musculoskeletal system, epilepsy, diabetes, gynaecological diseases and mental illness.
BMI, body mass index; C-section, caesarean section; VBAC, vaginal birth after caesarean section.