Table 1. Demographics and clinical characteristics in the study groups.
| Characteristics | Reference group (n = 338,109) |
HPV infection groups | Treated group (n = 23,185) |
Subsequent CIN2+ group (n = 33,760) |
|
|---|---|---|---|---|---|
| Cytology (n = 11,727) |
HPV test (n = 2,550) |
||||
| Age at delivery (years) | |||||
| <21 | 858 (0.3) | 161 (1.4) | 12 (0.5) | 10 (0.0) | 1,205 (3.6) |
| 21–25 | 54,778 (16.2) | 2,673 (22.8) | 445 (17.5) | 1,276 (5.5) | 7,402 (21.9) |
| 26–30 | 148,021 (43.8) | 4,447 (37.9) | 875 (34.3) | 7,865 (33.9) | 12,099 (35.8) |
| 31–35 | 101,995 (30.2) | 3,080 (26.3) | 789 (30.9) | 9,279 (40.0) | 9,562 (28.3) |
| 36–40 | 29,344 (8.7) | 1,177 (10.0) | 368 (14.4) | 4,095 (17.7) | 3,144 (9.3) |
| >40 | 3,113 (0.9) | 189 (1.6) | 61 (2.4) | 660 (2.8) | 348 (1.0) |
| BMI class (kg/m2) | |||||
| Underweight (<18.5) | 6,886 (2.0) | 326 (2.8) | 79 (3.1) | 376 (1.6) | 882 (2.6) |
| Normal weight (18.5–24.9) | 193,930 (57.4) | 6,871 (58.6) | 1,587 (62.2) | 13,678 (59.0) | 19,233 (57.0) |
| Overweight (25–29.9) | 76,964 (22.8) | 2,461 (21.0) | 499 (19.6) | 5,153 (22.2) | 7,348 (21.8) |
| Obese (≥30) | 34,493 (10.2) | 1,160 (9.9) | 253 (9.9) | 1,868 (8.1) | 2,935 (8.7) |
| Missing | 25,836 (7.6) | 909 (7.8) | 132 (5.2) | 2,110 (9.1) | 3,362(10.0) |
| Smoking | |||||
| Never | 286,236 (84.7) | 8,582 (73.2) | 2,057 (80.7) | 16,735 (72.2) | 22,151 (65.6) |
| Before pregnancy | 25,166 (7.4) | 1,327 (11.3) | 260 (10.2) | 2,727 (11.8) | 4,415 (13.1) |
| In early pregnancy | 6,254 (1.8) | 530 (4.5) | 56 (2.2) | 1,079 (4.7) | 2,102 (6.2) |
| In the third trimester | 9,111 (2.7) | 941 (8.0) | 121 (4.7) | 1,732 (7.5) | 3,793 (11.2) |
| Missing | 11,342 (3.4) | 347 (3.0) | 56 (2.2) | 912 (3.9) | 1,299 (3.8) |
| Infant’s sex | |||||
| Boy | 174,095 (51.5) | 6,108 (52.1) | 1,322 (51.8) | 11,853 (51.1) | 17,297 (51.2) |
| Girl | 164,000 (48.5) | 5,618 (47.9) | 1,228 (48.2) | 11,331 (48.9) | 16,462 (48.8) |
| Missing | 14 | 1 | 0 | 1 | 1 |
| Assisted reproduction1 | 9,341 (2.8) | 153 (1.3) | 46 (1.8) | 934 (4.0) | 434 (1.3) |
| Employment | |||||
| Full-time | 181,520 (53.7) | 5,728 (48.8) | 1,458 (57.2) | 14,315 (61.7) | 14,719 (43.6) |
| Part-time | 79,475 (23.5) | 2,469 (21.1) | 438 (17.2) | 4,278 (18.5) | 8,390 (24.9) |
| None | 47,200 (14.0) | 2,388 (20.4) | 449 (17.6) | 2,359 (10.2) | 6,605 (19.6) |
| Missing | 29,914 (8.8) | 1,142 (9.7) | 205 (8.0) | 2,233 (9.6) | 4,046 (12.0) |
| Parity | |||||
| 0 | 163,533 (48.4) | 6,479 (55.2) | 1,481 (58.1) | 13,425 (57.9) | 12,730 (37.7) |
| 1 | 129,737 (38.4) | 3,407 (29.1) | 724 (28.4) | 5,968 (25.7) | 14,547 (43.1) |
| 2 | 36,004 (10.6) | 1,308 (11.2) | 257 (10.1) | 2,788 (12.0) | 4,826 (14.3) |
| 3 | 6,780 (2.0) | 354 (3.0) | 54 (2.1) | 751 (3.2) | 1,187 (3.5) |
| >3 | 2,055 (0.6) | 179 (1.5) | 34 (1.3) | 253 (1.1) | 470 (1.4) |
| Marital status | |||||
| Cohabiting | 312,277 (92.4) | 10,286 (87.7) | 2,252 (88.3) | 20,777 (89.6) | 29,551 (87.5) |
| Single | 3,625 (1.1) | 346 (3.0) | 63 (2.5) | 443 (1.9) | 1,007 (3.0) |
| Other | 7,369 (2.2) | 626 (5.3) | 126 (4.9) | 792 (3.4) | 1,605 (4.8) |
| Missing | 14,838 (4.4) | 469 (4.0) | 109 (4.3) | 1,173 (5.1) | 1,597 (4.7) |
| Concurrent disease2 | |||||
| Renal disease | 1,326 (0.4) | 63 (0.5) | 17 (0.7) | 110 (0.5) | 184 (0.5) |
| Diabetes | 1,864 (0.6) | 69 (0.6) | 14 (0.5) | 104 (0.4) | 144 (0.4) |
| Epilepsy | 1,519 (0.4) | 66 (0.6) | 15 (0.6) | 121 (0.5) | 176 (0.5) |
| Chronic hypertension | 1,218 (0.4) | 39 (0.3) | 12 (0.5) | 99 (0.4) | 108 (0.3) |
| Education level3 | |||||
| Primary school, up to 9 years | 20,947 (6.2) | 1,439 (12.3) | 234 (9.2) | 1,798 (7.8) | 4,820 (14.3) |
| Secondary | 136,656 (40.4) | 5,329 (45.54) | 967 (37.9) | 10,092 (43.5) | 17,386 (51.5) |
| Post-secondary < 3 years | 46,648 (13.8) | 1,525 (13.0) | 358 (14.0) | 3,438 (14.8) | 4,007 (11.9) |
| Post-secondary ≥ 3 years | 132,012 (39.0) | 3,294 (28.1) | 971 (38.1) | 7,806 (33.7) | 7,148 (21.2) |
| Missing | 1,846 (0.5) | 140 (1.2) | 20 (0.8) | 51 (0.2) | 399 (1.2) |
| Country of birth | |||||
| Sweden | 290,269 (85.9) | 9,597 (81.8) | 2,053 (80.5) | 21,395 (92.3) | 29,724 (88.0) |
| Europe | 20,091 (5.9) | 872 (7.4) | 181 (7.1) | 1,017 (4.4) | 2,233 (6.6) |
| Asia | 19,105 (5.7) | 784 (6.7) | 188 (7.4) | 495 (2.1) | 1,213 (3.6) |
| America/Oceania | 3,253 (1.0) | 167 (1.4) | 47 (1.8) | 207 (0.9) | 381 (1.1) |
| Africa | 5,297 (1.6) | 297 (2.5) | 80 (3.1) | 70 (0.3) | 203 (0.6) |
| Missing | 94 (0) | 10 (0.1) | 1 (0.0) | 1 (0) | 6 (0.0) |
| Year of delivery | |||||
| 1999–2001 | 37,540 (11.1) | 1,346 (11.5) | 0 | 3,097 (13.4) | 6,389 (18.9) |
| 2002–2004 | 39,384 (11.6) | 1,250 (10.7) | 0 | 3,268 (14.1) | 6,372 (18.9) |
| 2005–2007 | 43,310 (12.8) | 1,198 (10.2) | 5 (0.2) | 3,368 (14.5) | 6,595 (19.5) |
| 2008–2010 | 53,847 (15.9) | 1,544 (13.2) | 76 (3.0) | 3,872 (16.7) | 6,566 (19.4) |
| 2011–2013 | 66,932 (19.8) | 2,533 (21.6) | 542 (21.3) | 4,259 (18.4) | 5,494 (16.3) |
| 2014–2016 | 97,096 (28.7) | 3,856 (32.9) | 1,927 (75.6) | 5,321 (23.0) | 2,344 (6.9) |
| Highest disposable household income in 3 years preceding delivery | |||||
| Lowest tertile | 44,834 (13.3) | 2,674 (22.8) | 610 (23.9) | 2,555 (11.0) | 6,320 (18.7) |
| Middle tertile | 100,738 (29.8) | 3,882 (33.1) | 758 (29.7) | 6,217 (26.8) | 11,007 (32.6) |
| Highest tertile | 192,535 (56.9) | 5,171 (44.1) | 1,181 (46.3) | 14,413 (62.2) | 16,426 (48.7) |
| Gestational age estimation method | |||||
| Ultrasound | 309,355 (91.5) | 10,828 (92.3) | 2,429 (95.3) | 20,836 (89.9) | 30,148 (89.3 |
| Last menstrual period | 15,200 (4.5) | 474 (4.0) | 45 (1.8) | 1,230 (5.3) | 2,024 (6.0) |
| Other4 | 13,554 (4.0) | 425 (3.6) | 76 (3.0) | 1,119 (4.8) | 1,588 (4.7) |
| Cytology diagnosis | |||||
| Low grade | 9,916 (84.6) | ||||
| High grade | 1,811 (15.4) | ||||
| Time period of CIN3 diagnosis | |||||
| 1978–1985 | 76 (0.3) | ||||
| 1986–1995 | 2,467 (10.6) | ||||
| 1996–2016 | 20,642 (89.0) | ||||
| Interval from CIN3 diagnosis to delivery (years) | |||||
| Mean (SD) | 4.4 (3.4) | ||||
| Median (IQR) | 3.4 (1.9–6.1) | ||||
| Interval from delivery to diagnosis of CIN2/CIN3/AIS/cancer (years) | |||||
| Mean (SD) | 4.3 (3.7) | ||||
| Median (IQR) | 3.2 (1.4–6.2) | ||||
Data are presented as number (percentage) unless otherwise specified. Percentages are based on those with available data. Percentages of missing are based on the total numbers.
1Treatment to achieve pregnancy.
2As reported in antenatal care records. Missing values were interpreted as the woman not having any concurrent disease, in accordance with how data are registered in antenatal care records.
3Highest education level at time of delivery.
4Ultrasound, last menstrual period, and/or estimation of gestational age at delivery ward.
AIS, adenocarcinoma in situ; BMI, body mass index; CIN, cervical intraepithelial neoplasia; IQR, interquartile range; SD, standard deviation.