Table 2. Counts and SUID Rates for Exposure Variable and Covariates.
| Characteristic | No. (%) | SUID rate, No./1000 births | Prepregnancy maternal BMI, mean (SD) | |
|---|---|---|---|---|
| SUID (n = 16 545) | Controls (n = 18 841 149) | |||
| Maternal BMI | ||||
| Underweight, <18.5 | 642 (3.9) | 613 535 (3.3) | 1.05 | 17.4 (0.9) |
| Normal, 18.5-24.9 | 5914 (35.7) | 7 935 244 (42.1) | 0.74 | 22.0 (1.7) |
| Overweight, 25.0-29.9 | 3812 (23.0) | 4 831 172 (25.6) | 0.79 | 27.2 (1.4) |
| Obesity class | ||||
| I, 30.0-34.9 | 2673 (16.2) | 2 704 181 (14.4) | 0.99 | 32.1 (1.4) |
| II, 35.0-39.9 | 1551 (9.4) | 1 326 907 (7.0) | 1.17 | 37.2 (1.4) |
| III, ≥40.0 | 1387 (8.4) | 944 553 (5.0) | 1.47 | 44.9 (4.5) |
| Unknown or not stated | 566 (3.4) | 485 557 (2.6) | 1.16 | NAa |
| Maternal age, y | ||||
| <20 | 1771 (10.7) | 971 977 (5.2) | 1.82 | 25.2 (6.0) |
| 20-24 | 5522 (33.4) | 3 765 640 (20.0) | 1.46 | 26.9 (6.8) |
| 25-29 | 4954 (29.9) | 5 475 346 (29.1) | 0.90 | 27.3 (6.9) |
| 30-34 | 2870 (17.3) | 5 335 263 (28.3) | 0.54 | 26.9 (6.6) |
| 35-39 | 1184 (7.2) | 2 689 862 (14.3) | 0.44 | 27.2 (6.6) |
| ≥40 | 244 (1.5) | 603 061 (3.2) | 0.40 | 27.4 (6.5) |
| Maternal raceb | ||||
| American Indian or Alaska Native | 370 (2.2) | 182 618 (1.0) | 2.02 | 28.8 (7.0) |
| Asian | 280 (1.7) | 1 264 298 (6.7) | 0.22 | 23.8 (4.6) |
| Black | 5292 (32.0) | 2 954 743 (15.7) | 1.79 | 28.7 (7.5) |
| Native Hawaiian or Other Pacific Islander | 88 (0.5) | 59 151 (0.3) | 1.49 | 29.7 (7.2) |
| White | 9784 (59.1) | 13 897 967 (73.8) | 0.70 | 26.9 (6.5) |
| >1 Race | 731 (4.4) | 482 323 (2.6) | 1.51 | 27.4 (7.1) |
| Unknown or not stated | 0 | 49 (0.0) | 0.00 | NAa |
| Maternal ethnicityb | ||||
| Central and South American | 206 (1.2) | 711 519 (3.8) | 0.29 | 26.5 (5.5) |
| Cuban | 47 (0.3) | 111 524 (0.6) | 0.42 | 26.2 (5.8) |
| Mexican | 1349 (8.2) | 2 551 701 (13.5) | 0.53 | 27.9 (6.4) |
| Non-Hispanic | 14 081 (85.1) | 14 279 562 (75.8) | 0.99 | 26.8 (6.8) |
| Puerto Rican | 294 (1.8) | 330 147 (1.8) | 0.89 | 27.9 (7.0) |
| Other or unknown Hispanic origin | 431 (2.6) | 694 518 (3.7) | 0.62 | 27.6 (6.5) |
| Unknown or not stated | 137 (0.8) | 162 178 (0.9) | 0.84 | 26.1 (6.2) |
| Maternal education | ||||
| ≤8th Grade | 384 (2.3) | 612 339 (3.3) | 0.63 | 27.1 (5.8) |
| 9th-12th Grade with no diploma | 3570 (21.6) | 1 864 355 (9.9) | 1.91 | 27.1 (6.9) |
| High school or GED | 6402 (38.7) | 4 747 905 (25.2) | 1.35 | 27.7 (7.1) |
| Some college | 3868 (23.4) | 3 814 866 (20.2) | 1.01 | 28.0 (7.2) |
| Associate degree | 819 (5.0) | 1 546 121 (8.2) | 0.53 | 27.7 (6.9) |
| Bachelor’s degree | 888 (5.4) | 3 782 201 (20.1) | 0.23 | 25.8 (5.9) |
| ≥Master’s degree | 397 (2.4) | 2 227 840 (11.8) | 0.18 | 25.2 (5.5) |
| Unknown or not stated | 217 (1.3) | 245 522 (1.3) | 0.88 | 26.4 (6.2) |
| Maternal birthplace | ||||
| Within the 50 US states | 15 305 (92.5) | 14 536 052 (77.2) | 1.05 | 27.3 (7.0) |
| Outside the US, including possessions | 1189 (7.2) | 4 268 517 (22.7) | 0.28 | 25.8 (5.5) |
| Unknown or not stated | 51 (0.3) | 36 580 (0.2) | 1.39 | 26.3 (6.3) |
| Marital status | ||||
| Married | 4601 (27.8) | 10 486 952 (55.7) | 0.44 | 26.7 (6.5) |
| Unmarried | 11 301 (68.3) | 6 992 539 (37.1) | 1.61 | 27.5 (7.1) |
| Unknown or not stated | 643 (3.9) | 1 361 658 (7.2) | 0.47 | 26.7 (6.3) |
| Maternal smoking | ||||
| Nonsmoker | 11 357 (68.6) | 17 039 043 (90.4) | 0.67 | 26.9 (6.6) |
| Continued | 4275 (25.8) | 1 255 309 (6.7) | 3.39 | 27.2 (7.3) |
| Quit | 634 (3.8) | 408 349 (2.2) | 1.55 | 27.8 (7.2) |
| Started | 80 (0.5) | 23 187 (0.1) | 3.44 | 27.6 (7.3) |
| Unknown or not stated | 199 (1.2) | 115 261 (0.6) | 1.72 | 27.2 (6.9) |
| Paternal age, y | ||||
| <20 | 569 (3.4) | 335 801 (1.8) | 1.69 | 25.0 (5.9) |
| 20-24 | 2766 (16.7) | 2 117 102 (11.2) | 1.30 | 26.7 (6.7) |
| 25-29 | 3283 (19.8) | 4 059 514 (21.5) | 0.81 | 27.2 (6.8) |
| 30-34 | 2474 (15.0) | 4 931 982 (26.2) | 0.50 | 26.8 (6.5) |
| 35-39 | 1415 (8.6) | 3 251 276 (17.3) | 0.44 | 26.8 (6.5) |
| 40-44 | 556 (3.4) | 1 283 588 (6.8) | 0.43 | 27.2 (6.6) |
| ≥45 | 375 (2.3) | 653 591 (3.5) | 0.57 | 27.1 (6.6) |
| Unknown or not stated | 5107 (30.9) | 2 208 295 (11.7) | 2.31 | 27.8 (7.4) |
| Paternal raceb | ||||
| American Indian or Alaska Native | 210 (1.3) | 123 773 (0.7) | 1.69 | 28.6 (7.0) |
| Asian | 206 (1.2) | 1 044 188 (5.5) | 0.20 | 23.8 (4.7) |
| Black | 3369 (20.4) | 2 288 753 (12.1) | 1.47 | 28.9 (7.5) |
| Native Hawaiian or Other Pacific Islander | 78 (0.5) | 47 672 (0.3) | 1.63 | 29.9 (7.4) |
| White | 6471 (39.1) | 11 549 341 (61.3) | 0.56 | 26.7 (6.4) |
| >1 Race | 418 (2.5) | 377 042 (2.0) | 1.11 | 26.8 (6.7) |
| Unknown or not stated | 5793 (35.0) | 3 410 380 (18.1) | 1.70 | 27.7 (7.1) |
| Payment source | ||||
| Private insurance | 3487 (21.1) | 9 249 211 (49.1) | 0.38 | 26.5 (6.4) |
| Medicaid | 11 881 (71.8) | 7 982 328 (42.4) | 1.49 | 27.7 (7.1) |
| Self-pay | 499 (3.0) | 763 262 (4.1) | 0.65 | 25.6 (5.7) |
| Other | 563 (3.4) | 725 296 (3.8) | 0.78 | 26.7 (6.2) |
| Unknown or not stated | 115 (0.7) | 121 052 (0.6) | 0.95 | 26.7 (6.5) |
| Live birth order | ||||
| 1 | 4291 (25.9) | 7 139 004 (37.9) | 0.60 | 26.2 (6.5) |
| 2 | 4886 (29.5) | 6 032 914 (32.0) | 0.81 | 27.0 (6.7) |
| 3 | 3528 (21.3) | 3 220 718 (17.1) | 1.09 | 27.6 (6.8) |
| 4 | 1923 (11.6) | 1 396 608 (7.4) | 1.38 | 28.2 (6.9) |
| 5 | 965 (5.8) | 548 977 (2.9) | 1.75 | 28.5 (6.9) |
| ≥6 | 878 (5.3) | 443 380 (2.4) | 1.98 | 28.7 (7.0) |
| Unknown or not stated | 74 (0.4) | 59 548 (0.3) | 1.24 | 26.7 (6.5) |
| Infant sex | ||||
| Female | 6888 (41.6) | 9 207 653 (48.9) | 0.75 | 27.0 (6.7) |
| Male | 9657 (58.4) | 9 633 496 (51.1) | 1.00 | 27.0 (6.7) |
| GA at birth, wk | ||||
| 28-31 | 500 (3.0) | 166 883 (0.9) | 2.99 | 28.0 (7.4) |
| 32-36 | 2936 (17.7) | 1 571 760 (8.3) | 1.86 | 27.7 (7.3) |
| ≥37 | 13 109 (79.2) | 17 102 506 (90.8) | 0.77 | 26.9 (6.6) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); GA, gestational age; GED, General Educational Development test; NA, not applicable; SUID, sudden unexpected infant death.
a
Not estimable due to all missing values.
b
Data were obtained from the Centers for Disease Control and Prevention, which aggregates and recodes these data from birth certificates.