Table 1.
Characteristics of participants with singleton preterm birth and low birthweight (Total n = 3,418,028).
| Variables | Preterm Birth Groups | Low Birthweight Groups | ||||
|---|---|---|---|---|---|---|
| Case n = 280,206 (8.2%) |
Control n = 3,137,822 (91.8%) |
p Value | Case n = 221,260 (6.5%) |
Control n = 3,196,768 (93.5%) |
p Value | |
| Race/ethnicity | <0.001 | <0.001 | ||||
| Non-Hispanic White | 127,646 (7.2) | 1,644,164 (92.8) | 90,426 (5.1) | 1,681,384 (94.9) | ||
| Non-Hispanic Black | 57,927 (11.8) | 434,420 (88.2) | 57,152 (11.6) | 435,195 (88.4) | ||
| Hispanic | 68,741 (8.4) | 753,197 (91.6) | 50,204 (6.1) | 771,734 (93.9) | ||
| Other races a | 25,892 (7.8) | 306,041 (92.2) | 23,478 (7.1) | 308,455 (92.9) | ||
| Age, years | <0.001 | <0.001 | ||||
| <20 | 14,541 (9.1) | 145,921 (90.9) | 14,046 (8.7) | 146,416 (91.3) | ||
| 20–24 | 53,262 (8.2) | 595,299 (91.8) | 45,939 (7.1) | 602,622 (92.9) | ||
| 25–29 | 75,495 (7.6) | 912,237 (92.4) | 59,506 (6.0) | 928,226 (94.0) | ||
| 30–34 | 76,026 (7.7) | 915,057 (92.3) | 57,492 (5.8) | 933,591 (94.2) | ||
| ≥35 | 60,882 (9.7) | 569,308 (90.3) | 44,277 (7.0) | 585,913 (93.0) | ||
| Education level | <0.001 | <0.001 | ||||
| High school or less | 123,482 (9.4) | 1,186,621 (90.6) | 103,094 (7.9) | 1,207,009 (92.1) | ||
| Some college | 83,265 (8.7) | 877,047 (91.3) | 63,442 (6.6) | 896,870 (93.4) | ||
| Bachelor’s or higher | 73,459 (6.4) | 1,074,154 (93.6) | 54,724 (4.8) | 1,092,889 (95.2) | ||
| Marital status | <0.001 | <0.001 | ||||
| Married | 130,352 (7.2) | 1,677,786 (92.8) | 93,512 (5.2) | 1,714,626 (94.8) | ||
| Unmarried | 149,854 (9.3) | 1,460,036 (90.7) | 127,748 (7.9) | 1,482,142 (92.1) | ||
| Health insurance | <0.001 | <0.001 | ||||
| Medicaid/other public | 145,937 (9.4) | 1,405,608 (90.6) | 122,152 (7.9) | 1,429,393 (92.1) | ||
| Private | 123,658 (7.2) | 1,595,051 (92.8) | 91,095 (5.3) | 1,627,614 (94.7) | ||
| Self-pay/none | 10,611 (7.2) | 137,163 (92.8) | 8013 (5.4) | 139,761 (94.6) | ||
| Parity | <0.001 | <0.001 | ||||
| Primipara | 109,508 (8.2) | 1,217,530 (91.8) | 100,775 (7.6) | 1,226,263 (92.4) | ||
| Multipara | 170,698 (16.4) | 1,920,292 (83.6) | 120,485 (11.5) | 1,970,505 (88.5) | ||
| Prior preterm birth | 32,381 (26.8) | 88,569 (73.2) | <0.001 | 21,145 (17.5) | 99,805 (82.5) | <0.001 |
| Gestational diabetes | 26,960 (11.5) | 207,106 (88.5) | <0.001 | 16,252 (6.9) | 217,814 (93.1) | <0.001 |
| Gestational hypertension | 48,880 (18.9) | 209,848 (81.1) | <0.001 | 39,329 (15.2) | 219,399 (84.8) | <0.001 |
| Smoking | 24,751 (12.2) | 178,666 (87.8) | <0.001 | 24,930 (12.3) | 178,487 (87.7) | <0.001 |
| STIs | <0.001 | <0.001 | ||||
| Chlamydia | 6477 (10.0) | 57,966 (90.0) | 5989 (9.3) | 58,454 (90.7) | ||
| Gonorrhea | 1348 (12.3) | 9565 (87.7) | 1283 (11.8) | 9630 (88.2) | ||
| Syphilis | 729 (14.6) | 4255 (85.4) | 636 (12.8) | 4348 (87.2) | ||
| PNC utilization status b | <0.001 | <0.001 | ||||
| PNC adequate | 212,556 (8.0) | 2,440,860 (92.0) | 161,986 (6.1) | 2,491,430 (93.9) | ||
| PNC inadequate | 67,650 (8.8) | 696,962 (91.2) | 59,274 (7.7) | 705,338 (92.3) | ||
| Infant sex | <0.001 | <0.001 | ||||
| Male | 150,375 (8.6) | 1,598,990 (91.4) | 103,388 (5.9) | 1,645,977 (94.1) | ||
| Female | 129,831 (7.8) | 1,538,832 (92.2) | 117,872 (7.1) | 1,550,791 (92.9) | ||
a Other races: Asian, American Indian/Alaska Native, Native Hawaiian, Pacific Islander or mixed races; STIs: sexually transmitted infections; b PNC: prenatal care; PNC adequate: early and >10 visits; PNC inadequate: late and ≤10 visits.