Table 1 Baseline characteristics of the study participants according to maternal HDP
Characteristics | No HDP | Preeclampsia or eclampsia | Chronic hypertension | Gestational hypertension | Total |
|---|---|---|---|---|---|
N | 2,346,055 (95.8) | 68,800 (2.8) | 15,336 (0.6) | 18,562 (0.8) | 2,448,753 (100.0) |
Outcome | |||||
 No | 2,322,410 (99.0) | 67,881 (98.7) | 15,246 (99.4) | 18,324 (98.7) | 2,423,861 (99.0) |
 Yes | 23,645 (1.0) | 919 (1.3) | 90 (0.6) | 238 (1.3) | 24,892 (1.0) |
Singleton | |||||
 No | 74,687 (3.2) | 6350 (9.2) | 677 (4.4) | 811 (4.4) | 82,525 (3.4) |
 Yes | 2,271,368 (96.8) | 62,450 (90.8) | 14,659 (95.6) | 17,751 (95.6) | 2,366,228 (96.6) |
Sex | |||||
 Male | 1,203,772 (51.3) | 35,799 (52.0) | 7908 (51.6) | 9638 (51.9) | 1,257,117 (51.3) |
 Female | 1,142,283 (48.7) | 33,001 (48.0) | 7428 (48.4) | 8924 (48.1) | 1,191,636 (48.7) |
Calendar year of birth | |||||
 1978–1987 | 478,305 (20.4) | 14,923 (21.7) | 709 (4.6) | 3569 (19.2) | 497,506 (20.3) |
 1988–1997 | 625,820 (26.7) | 18,144 (26.4) | 1551 (10.1) | 3589 (19.3) | 649,104 (26.5) |
 1998–2007 | 618,242 (26.4) | 16,390 (23.8) | 4981 (32.5) | 4258 (22.9) | 643,871 (26.3) |
 2008–2018 | 623,688 (26.6) | 19,343 (28.1) | 8095 (52.8) | 7146 (38.5) | 658,272 (26.9) |
Maternal country of origin | |||||
 Others | 284,848 (12.1) | 5477 (8.0) | 1337 (8.7) | 1317 (7.1) | 292,979 (12.0) |
 Danish origin | 2,057,394 (87.7) | 63,236 (91.9) | 13,992 (91.2) | 17,217 (92.8) | 2,151,839 (87.9) |
 Unknown | 3813 (0.2) | 87 (0.1) | 7 (0.1) | 28 (0.2) | 3935 (0.2) |
Maternal parity | |||||
 1 | 1,045,191 (44.6) | 45,295 (65.8) | 5094 (33.2) | 10,939 (58.9) | 1,106,519 (45.2) |
 2 | 879,045 (37.5) | 15,920 (23.1) | 6477 (42.2) | 4974 (26.8) | 906,416 (37.0) |
 ≥3 | 421,819 (18.0) | 7585 (11.0) | 3765 (24.6) | 2649 (14.3) | 435,818 (17.8) |
Maternal age at childbirth (years) | |||||
 <20 | 51,693 (2.2) | 1990 (2.9) | 46 (0.3) | 253 (1.4) | 53,982 (2.2) |
 20–24 | 398,027 (17.0) | 13,852 (20.1) | 953 (6.2) | 2637 (14.2) | 415,469 (17.0) |
 25–29 | 853,251 (36.4) | 24,604 (35.8) | 3731 (24.3) | 6148 (33.1) | 887,734 (36.3) |
 30–34 | 715,587 (30.5) | 18,162 (26.4) | 5698 (37.2) | 5692 (30.7) | 745,139 (30.4) |
 35+ | 327,497 (14.0) | 10,192 (14.8) | 4908 (32.0) | 3832 (20.6) | 346,429 (14.1) |
Maternal BMI during pregnancy | |||||
 <18.5 | 37,158 (4.3) | 578 (2.2) | 239 (2.3) | 160 (1.8) | 38,135 (4.2) |
 18.5–24.9 | 524,766 (60.4) | 11,694 (45.4) | 4699 (44.5) | 3754 (41.5) | 544,913 (59.6) |
 25.0–29.9 | 175,210 (20.2) | 6554 (25.4) | 2495 (23.6) | 2316 (25.6) | 186,575 (20.4) |
 ≥30.0 | 99,285 (11.4) | 6181 (24.0) | 2793 (26.4) | 2593 (28.7) | 110,852 (12.1) |
 Unknown | 32,208 (3.7) | 775 (3.0) | 343 (3.3) | 219 (2.4) | 33,545 (3.7) |
Maternal smoking during pregnancy a | |||||
 No | 1,319,267 (78.0) | 39,592 (81.2) | 12,040 (84.1) | 11,751 (84.4) | 1,382,650 (78.2) |
 Yes | 314,002 (18.6) | 6863 (14.1) | 1768 (12.4) | 1739 (12.5) | 324,372 (18.3) |
 Unknown | 58,196 (3.4) | 2288 (4.7) | 505 (3.5) | 433 (3.1) | 61,422 (3.5) |
Maternal education at childbirth, years | |||||
 0–9 | 600,423 (25.6) | 19,001 (27.6) | 2669 (17.4) | 4059 (21.9) | 626,152 (25.6) |
 10–14 | 1,004,808 (42.8) | 30,677 (44.6) | 6759 (44.1) | 8342 (44.9) | 1,050,586 (42.9) |
 15+ | 701,709 (29.9) | 18,328 (26.6) | 5760 (37.6) | 5919 (31.9) | 731,716 (29.9) |
 Unknown | 39,115 (1.7) | 794 (1.2) | 148 (1.0) | 242 (1.3) | 40,299 (1.6) |
Maternal cohabitation at childbirth | |||||
 No | 1,074,662 (45.8) | 35,675 (51.9) | 6861 (44.7) | 9024 (48.6) | 1,126,222 (46.0) |
 Yes | 1,270,421 (54.2) | 33,102 (48.1) | 8473 (55.3) | 9530 (51.3) | 1,321,526 (54.0) |
 Unknown | 972 (0.04) | 23 (0.03) | 2 (0.01) | 8 (0.04) | 1005 (0.00) |
Maternal residence at birth | |||||
 Copenhagen | 274,998 (11.7) | 7778 (11.3) | 1577 (10.3) | 2121 (11.4) | 286,474 (11.7) |
 Big cities ≥ 100,000 inhabitants | 307,175 (13.1) | 9446 (13.7) | 2014 (13.1) | 3034 (16.4) | 321,669 (13.1) |
 Other | 1,763,882 (75.2) | 51,576 (75.0) | 11,745 (76.6) | 13,407 (72.2) | 1,840,610 (75.2) |
Maternal income at birth | |||||
 Less than lowest tertiles | 424,799 (18.8) | 10,599 (15.9) | 2530 (16.6) | 2524 (14.1) | 440,452 (18.6) |
 Lowest and middle tertiles | 611,191 (27.0) | 19,029 (28.6) | 3495 (22.9) | 4616 (25.7) | 638,331 (27.0) |
 Middle and highest tertiles | 611,914 (27.1) | 18,913 (28.4) | 4596 (30.1) | 5489 (30.6) | 640,912 (27.1) |
 More than highest tertiles | 613,931 (27.1) | 17,944 (27.0) | 4649 (30.4) | 5301 (29.6) | 641,825 (27.2) |
 Unknown | 515 (0.02) | 9 (0.01) | 1 (0.01) | 3 (0.02) | 528 (0.02) |
Paternal diabetes history before childbirth | |||||
 No | 2,309,753 (98.5) | 67,379 (97.9) | 15,004 (97.8) | 18,177 (97.9) | 2,410,313 (98.4) |
 Yes | 13,993 (0.6) | 494 (0.7) | 141 (0.9) | 155 (0.8) | 14,783 (0.6) |
 Unknown | 22,309 (1.0) | 927 (1.4) | 191 (1.3) | 230 (1.2) | 23,657 (1.0) |
Maternal diabetes history before childbirth | |||||
 No | 2,306,898 (98.3) | 65,825 (95.7) | 13,932 (90.9) | 17,539 (94.5) | 2,404,194 (98.2) |
 Yes | 39,157 (1.7) | 2975 (4.3) | 1404 (9.2) | 1023 (5.5) | 44,559 (1.8) |
Paternal hypertension history before childbirth | |||||
 No | 2,313,170 (98.6) | 67,514 (98.1) | 15,011 (97.9) | 18,216 (98.1) | 2,413,911 (98.6) |
 Yes | 10,576 (0.5) | 359 (0.5) | 134 (0.9) | 116 (0.6) | 11,185 (0.5) |
 Unknown | 22,309 (1.0) | 927 (1.4) | 191 (1.3) | 230 (1.2) | 23,657 (1.0) |