Table 1.
Descriptive statistics of patients without and with IMIDs prior to pregnancy.
| Variable | Patients without an IMIDs prior to pregnancy (n = 365,075) | Patients with an IMIDs prior to pregnancy (n = 5784) |
|---|---|---|
| Pregnancy outcomes | ||
| Gestational age at birth (days) | 275.0 (12.8) | 274.0 (13.8) |
| Preterm birth | 26,371 (7.7) | 539 (9.3) |
| Low birth weight | 18,365 (5.4) | 393 (6.8) |
| Small for gestational age | 41,316 (12.1) | 778 (13.5) |
| Caesarean section | 103,772 (30.2) | 2012 (34.8) |
| Maternal characteristics | ||
| Maternal age | 31.0 (5.8) | 32.7 (5.3) |
| Age group | ||
| 18–24 | 60,472 (17.6) | 557 (9.6) |
| 25–29 | 87,759 (25.6) | 1225 (21.2) |
| 30–34 | 112,308 (32.7) | 2163 (37.4) |
| 35–39 | 66,545 (19.4) | 1478 (25.6) |
| 40 or older | 16,073 (4.7) | 361 (6.2) |
| Race group | ||
| American Indian or Alaska Native | 4437 (1.3) | 74 (1.3) |
| Asian | 27,513 (8.0) | 332 (5.7) |
| Black or African American | 14,550 (4.2) | 164 (2.8) |
| Native Hawaiian or other Pacific Islander | 3953 (1.2) | 48 (0.8) |
| White | 215,895 (62.9) | 4227 (73.1) |
| More than one race | 17,127 (5.0) | 290 (5.0) |
| Other | 57,520 (16.8) | 633 (10.9) |
| Missing | 2162 (0.6) | 16 (0.3) |
| Ethnicity | ||
| Hispanic or Latino | 72,607 (21.2) | 665 (11.5) |
| Not Hispanic nor Latino | 262,950 (76.6) | 4986 (86.2) |
| Unknown/unreported | 7536 (2.2) | 133 (2.3) |
| BMI category | ||
| Underweight | 2823 (0.8) | 62 (1.1) |
| Normal | 49,346 (14.4) | 985 (17.0) |
| Overweight | 29,614 (8.6) | 599 (10.4) |
| Obese | 29,618 (8.6) | 685 (11.8) |
| Missing | 231,756 (67.5) | 3453 (59.7) |
| Insurance | ||
| Commercial | 158,995 (46.3) | 3191 (55.2) |
| Medicaid/Medicare | 181,892 (53.0) | 2575 (44.5) |
| Self pay | 76 (0.0) | 0 (0.0) |
| Missing | 2194 (0.6) | 18 (0.3) |
| Smoker | 24,414 (7.1) | 511 (8.8) |
| Illegal drug user | 25,745 (7.5) | 578 (10.0) |
| Alcohol user | 60,516 (17.6) | 1678 (29.0) |
| Vulnerability index of socioeconomic status | 0.4 (0.2) | 0.4 (0.2) |
| Vulnerability index of housing composition | 0.4 (0.3) | 0.4 (0.3) |
| Vulnerability index of minority status and language | 0.6 (0.2) | 0.6 (0.2) |
| Vulnerability index of housing type and transportation | 0.6 (0.3) | 0.6 (0.3) |
| Rural/urban classification | ||
| Metropolitan | 289,998 (84.5) | 4952 (85.6) |
| Micropolitan | 16,355 (4.8) | 268 (4.6) |
| Small Town | 5564 (1.6) | 134 (2.3) |
| Rural | 4378 (1.3) | 84 (1.5) |
| Missing | 26,862 (7.8) | 346 (6.0) |
| Pregnancy characteristics | ||
| Gravidity | ||
| 1 | 78,337 (22.8) | 1240 (21.4) |
| 2–4 | 189,217 (55.1) | 3052 (52.8) |
| 5≤ | 39,838 (11.6) | 804 (13.9) |
| Missing | 35,765 (10.4) | 688 (11.9) |
| Parity | ||
| 0 | 42,250 (12.3) | 717 (12.4) |
| 1 | 121,735 (35.5) | 2006 (34.7) |
| 2–4 | 135,366 (39.4) | 2254 (39.0) |
| 5≤ | 8041 (2.3) | 119 (2.1) |
| Missing | 35,765 (10.4) | 688 (11.9) |
| History of preterm delivery | ||
| Yes | 71,978 (21.0) | 1232 (21.3) |
| No | 235,414 (68.6) | 3864 (66.8) |
| Missing | 35,765 (10.4) | 688 (11.9) |
| Fetal sex | ||
| Female | 156,624 (48.6) | 2622 (48.4) |
| Male | 165,401 (51.4) | 2791 (51.5) |
| Unknown | 48 (0.0) | 2 (0.0) |
| Other | 15 (0.0) | 1 (0.0) |
| Delivery year | ||
| 2013 | 20,462 (6.0) | 231 (4.0) |
| 2014 | 30,362 (8.8) | 346 (6.0) |
| 2015 | 34,310 (10.0) | 430 (7.4) |
| 2016 | 35,708 (10.4) | 495 (8.6) |
| 2017 | 35,239 (10.3) | 572 (9.9) |
| 2018 | 34,887 (10.2) | 640 (11.1) |
| 2019 | 36,192 (10.5) | 706 (12.2) |
| 2020 | 34,680 (10.1) | 715 (12.4) |
| 2021 | 39,015 (11.4) | 767 (13.3) |
| 2022 | 42,302 (12.3) | 882 (15.2) |
| Comorbidities | ||
| Diabetes: type 1 or type 2 | 2510 (0.7) | 88 (1.5) |
| Chronic kidney disease | 218 (0.1) | 18 (0.3) |
| Obesity | 10,296 (3.0) | 407 (7.0) |
| Chronic liver disease | 661 (0.2) | 30 (0.5) |
| Asthma | 17,978 (5.2) | 693 (12.0) |
| Depression | 31,365 (9.1) | 1276 (22.1) |
| Pneumonia | 3072 (0.9) | 119 (2.1) |
| Urinary tract infection | 35,578 (10.4) | 1086 (18.8) |
| Sexually transmitted disease | 5712 (1.7) | 203 (3.5) |
| Cardiovascular disease | 47,737 (13.9) | 2024 (35.0) |
| Sepsis | 1491 (0.4) | 81 (1.4) |
BMI, body mass index; IMID, immune-mediated inflammatory disease.
Variables are defined in Supplementary Table S2. SNOMED codes of diagnoses are listed in Supplementary Table S1. Mean and standard deviation are calculated for continuous variables. Proportions of each category are calculated for categorical variables.