Table 1.
Characteristics of the cohort of women* by childbirth group (n=492 504)
| Factors | B0 (n=453 532) | B1 (n=14 299) | B1+ (n=23 673) | P value† |
| n (%) | n (%) | n (%) | ||
| Age in 2004 (years) | <0.001 | |||
| 18 to 24 | 257 219 (56.7) | 3688 (25.8) | 5284 (21.4) | |
| 25 to 29 | 92 672 (20.4) | 4593 (32.1) | 10 354 (42.0) | |
| 30 to 34 | 56 233 (12.4) | 4089 (28.6) | 7614 (30.9) | |
| 35 to 39 | 47 408 (10.5) | 1929 (13.5) | 1421 (5.8) | |
| Country of birth | <0.001 | |||
| Sweden | 397 091 (87.6) | 12 388 (86.6) | 22 583 (91.5) | |
| Other Northern European | 4873 (1.1) | 200 (1.4) | 237 (1.0) | |
| Other European countries | 7432 (1.6) | 213 (1.5) | 242 (1.0) | |
| Rest of the world | 44 136 (9.7) | 1498 (10.5) | 1611 (6.5) | |
| Type of living area in 2004 | <0.001 | |||
| Large cities | 196 911 (43.4) | 6260 (43.8) | 10 882 (44.1) | |
| Medium-sized cities | 161 919 (35.7) | 4824 (33.7) | 8425 (34.2) | |
| Small cities/rural | 94 702 (20.9) | 3215 (22.5) | 5366 (21.8) | |
| Educational attainment in 2004 | <0.001 | |||
| Elementary (≤9 years) | 90 510 (20.0) | 1815 (12.7) | 1757 (7.1) | |
| High school (10 to 12 years) | 208 184 (45.9) | 6751 (47.2) | 9516 (38.6) | |
| University/college (≥13 years) | 154 838 (34.1) | 5733 (40.1) | 13 400 (54.3) | |
| Family situation in 2004 | <0.001 | |||
| Married or cohabitant | 20 295 (4.5) | 3212 (22.5) | 6843 (27.7) | |
| Single | 433 237 (95.5) | 11 087 (77.5) | 17 830 (72.3) | |
| Hospitalisation (at least 1 day during): | ||||
| Y−3 to Y−1 | 50 184 (11.1) | 8074 (56.5) | 13 145 (53.3) | <0.001 |
| Excluding ICD-10: O and Z30-Z39 | 49 040 (10.8) | 1726 (12.2) | 2210 (9.0) | <0.001 |
| Y+1 to Y+3 | 49 430 (10.9) | 13 975 (97.7) | 24 547 (99.5) | <0.001 |
| Excluding ICD-10: O and Z30-Z39 | 47 892 (10.6) | 1691 (11.8) | 1924 (7.8) | <0.001 |
| Y−3 to Y+3 | 14 865 (3.3) | 7773 (54.4) | 13 024 (52.8) | <0.001 |
| Excluding ICD-10: O and Z30-Z39 | 14 436 (3.2) | 439 (3.1) | 372 (1.5) | <0.001 |
| Specialised outpatient visit (at least one visit during): | ||||
| Y−3 to Y−1 | 256 677 (56.6) | 12 130 (84.8) | 19 916 (80.7) | <0.001 |
| Excluding ICD-10: O and Z30-Z39 | 254 531 (56.1) | 10 286 (71.9) | 16 323 (66.2) | <0.001 |
| Y+1 to Y+3 | 264 932 (58.4) | 9870 (69.0) | 19 625 (79.5) | <0.001 |
| Excluding ICD-10: O and Z30-Z39 | 261 766 (57.7) | 9063 (63.4) | 15 489 (62.8) | <0.001 |
| Y−3 to Y+3 | 180 667 (39.8) | 8737 (61.1) | 16 520 (67.0) | <0.001 |
| Excluding ICD-10: O and Z30-Z39 | 177 748 (39.2) | 7165 (50.1) | 11 376 (46.1) | <0.001 |
| At least one SA spell during: | ||||
| Y−3 to Y−1 | 54 013 (11.9) | 5840 (40.8) | 8802 (35.7) | <0.001 |
| Y+1 to Y+3 | 61 341 (13.5) | 2797 (19.6) | 7447 (30.2) | <0.001 |
| Y−3 to Y+3 | 90 849 (20.0) | 6740 (47.1) | 11 940 (48.4) | <0.001 |
| Disability pension any time during: | ||||
| Y−3 to Y−1 | 21 289 (4.7) | 351 (2.5) | 208 (0.8) | <0.001 |
| Y+1 to Y+3 | 27 453 (6.1) | 438 (3.1) | 238 (1.0) | <0.001 |
| Y−3 to Y+3 | 28 121 (6.2) | 467 (3.3) | 256 (1.0) | <0.001 |
B0=no childbirth in 2005 nor in the following 3 years+43 weeks; B1=first child in 2005 and no more deliveries in the following 3 years+43 weeks; B1+=first child in 2005 and at least one more delivery in the following 3 years+43 weeks; Y−3=3 years before delivery/index date; Y-−1=1 year before delivery/index date; Y+1=1 year after delivery/index date; Y+3=3 years after delivery/index date; T0=delivery date, or in the B0 group: 2 July 2005.
*Nulliparous women aged 18 to 39 years in December 2004 registered as residents in Sweden between 2002 and 2004.
†The p value corresponds to χ2 tests in case of categorical variables and to Wilcoxon tests in case of continuous/count variables.
SA, sickness absence.