Table 1. Baseline Covariates, Stratified by Gestational Diabetes (GD) Occurrence(s) in Each Respective Pregnancy.
| Covariate | Patients, No. (%)a | |||
|---|---|---|---|---|
| No GD (n = 396 660) | GD in first pregnancy (n = 10 920) | GD in second pregnancy (n = 16 145) | GD in both pregnancies (n = 8255) | |
| Prior history of gestational hypertension in either or both pregnanciesb | 29 550 (7.5) | 1275 (11.7) | 2160 (13.4) | 1160 (14.1) |
| Age of mother at second delivery, mean (SD), yc | 30.0 (4.5) | 30.9 (4.6) | 31.6 (4.7) | 32.0 (4.7) |
| Time between deliveries, y | ||||
| <2 | 124 800 (31.5) | 3525 (32.3) | 4055 (25.1) | 2530 (30.6) |
| 2 to <2.5 | 81 610 (20.6) | 2250 (20.6) | 2705 (16.8) | 1545 (18.7) |
| 2.5 to <3.5 | 103 195 (26.0) | 2710 (24.8) | 4010 (24.8) | 2090 (25.3) |
| ≥3.5 | 87 050 (21.9) | 2435 (22.3) | 5380 (33.3) | 2090 (25.3) |
| Material deprivation index, quintilesd | ||||
| 1 | 81 265 (20.5) | 2005 (18.4) | 2900 (18.0) | 1475 (17.9) |
| 2 | 83 975 (21.2) | 2285 (20.9) | 3250 (20.1) | 1630 (19.7) |
| 3 | 78 870 (19.9) | 2135 (19.6) | 3095 (19.2) | 1560 (18.9) |
| 4 | 74 525 (18.8) | 2125 (19.5) | 3155 (19.5) | 1625 (19.7) |
| 5 | 71 280 (18.0) | 2195 (20.1) | 3455 (21.4) | 1840 (22.3) |
| Social deprivation index, quintilesd | ||||
| 1 | 88 545 (22.3) | 2305 (21.1) | 3145 (19.5) | 1760 (21.3) |
| 2 | 85 620 (21.6) | 2250 (20.6) | 3255 (20.2) | 1615 (19.6) |
| 3 | 81 225 (20.5) | 2200 (20.1) | 3325 (20.6) | 1605 (19.4) |
| 4 | 72 980 (18.4) | 2110 (19.3) | 3155 (19.5) | 1685 (20.4) |
| 5 | 61 545 (15.5) | 1885 (17.3) | 2975 (18.4) | 1465 (17.7) |
| Backgrounde | ||||
| America, Australia, or Europe | 346 230 (87.3) | 8865 (81.2) | 12 280 (76.1) | 6040 (73.2) |
| Africa or Caribbean | 7565 (1.9) | 260 (2.4) | 465 (2.9) | 260 (3.2) |
| Arab-speaking regions | 14 840 (3.7) | 600 (5.5) | 1210 (7.5) | 665 (8.1) |
| Asia | 12 040 (3.0) | 640 (5.9) | 1190 (7.4) | 745 (9.0) |
| Other | 15 980 (4.0) | 555 (5.1) | 1005 (6.2) | 545 (6.6) |
| Comorbid conditions | ||||
| Mood disorders and alcohol or drug dependence | 16 315 (4.1) | 440 (4.0) | 850 (5.3) | 405 (4.9) |
| Thyroid disorder | 13 185 (3.3) | 450 (4.1) | 895 (5.5) | 480 (5.8) |
| Arthritis | 8265 (2.1) | 270 (2.5) | 435 (2.7) | 210 (2.5) |
| Asthma or COPD | 7735 (2.0) | 250 (2.3) | 425 (2.6) | 240 (2.9) |
| Small for gestational agef | ||||
| Neither pregnancy | 338 405 (85.3) | 9465 (86.7) | 14 120 (87.5) | 7235 (87.6) |
| First pregnancy only | 24 225 (6.1) | 630 (5.8) | 815 (5.1) | 445 (5.4) |
| Second pregnancy only | 24 240 (6.1) | 580 (5.3) | 890 (5.5) | 435 (5.3) |
| Both pregnancies | 9650 (2.4) | 240 (2.2) | 320 (2.0) | 135 (1.6) |
| Large for gestational agef | ||||
| Neither pregnancy | 339 910 (85.7) | 8735 (80.0) | 12 635 (78.3) | 6355 (77.0) |
| First pregnancy only | 23 290 (5.9) | 845 (7.7) | 1315 (8.1) | 710 (8.6) |
| Second pregnancy only | 23 145 (5.8) | 865 (7.9) | 1370 (8.5) | 690 (8.4) |
| Both pregnancies | 10 175 (2.6) | 470 (4.3) | 825 (5.1) | 495 (6.0) |
| Preterm birth | ||||
| Neither pregnancy | 361 365 (91.1) | 9725 (89.1) | 14 040 (87.0) | 7160 (86.7) |
| First pregnancy only | 18 155 (4.6) | 595 (5.5) | 1050 (6.5) | 530 (6.4) |
| Second pregnancy only | 13 050 (3.3) | 450 (4.1) | 720 (4.5) | 410 (5.0) |
| Both pregnancies | 4085 (1.0) | 150 (1.4) | 340 (2.1) | 155 (1.9) |
| History of paternal diabetesg | 3170 (0.8) | 110 (1.0) | 225 (1.4) | 140 (1.7) |
| History of paternal hypertensiong | 8385 (2.1) | 305 (2.8) | 480 (3.0) | 250 (3.0) |
Abbreviaton: COPD, chronic obstructive pulmonary disease.
Values are randomly rounded up or down to a multiple of 5 (for patient confidentiality purposes). Therefore, column sums for each baseline characteristic may not equal the total number of women in each level of the exposure due to this random rounding process.
Gestational hypertension was collapsed as a binary variable (absent or present in either or both pregnancies) as a measure to ensure the proportional hazards assumption was met when tested. When gestational hypertension status was categorized into 4 levels, similar to the primary GD exposure, the assumption was violated. The capture period for this comorbidity was between 20 weeks’ gestation to 12 weeks post partum of each respective pregnancy.
Age was not categorized and instead kept as a continuous variable.
Range from 1 (least deprived) to 5 (most deprived). A total of 7335 women were missing an assigned deprivation score.
Ethnocultural background based on the mother’s region of birth and reported preferred language. Women were categorized as European if born in North America, South America, Central America, Mexico, East/South/Southern/West Europe, or Australia and first language was English, French, or other European language; African or Caribbean if born in West/South/East/Central Africa or first language was of Caribbean or African descent; Arabic if born in the Arab league or first language was of Arabic or other North African or Southwest Asian descent; Asian if born in West/East/Central/South/Southeast/Pacific Asia or first language descends from these regions; or Other (does not fit into any other category), or if first language was of Indigenous descent.
A total of 150 offspring were missing birthweight required to derive offspring size.
Prior history in the father was defined as 1 or more inpatient and/or 2 or more outpatient International Statistical Classification of Diseases and Related Health Problems, Ninth and Tenth Revision codes for any form of diabetes or hypertension, respectively, that occurred during the period from 2 years before 20 weeks’ gestation in their partner’s first pregnancy to 12 weeks post partum in relationship to the second pregnancy.