| Characteristics | LBW prevalence (95% CI) | TLBW prevalence (95% CI) | PB prevalence (95% CI) |
| Mother’s race | |||
| White | 7.41 (7.08 to 7.74) | 4.15 (3.9 to 4.4) | 8.4 (8.1 to 8.8) |
| Black | 13.73 (13.31 to 14.17) | 7.6 (7.2 to 7.9) | 19.8 (19.3 to 20.3) |
| Oriental | 6.06 (3.48 to 10.18) | 3.7 (1.7 to 7.4) | 6.9 (4.1 to 11.2) |
| Other | 9.39 (8.48 to 10.38) | 5.5 (4.8 to 6.4) | 17.4 (16.2 to 18.7) |
| Mother’s age (years) | |||
| <20 | 12.79 (12.21 to 13.39) | 7.1 (6.6 to 7.6) | 17.9 (17.2 to 18.6) |
| 20–29 | 9.55 (9.23 to 9.88) | 5.2 (5.0 to 5.5) | 13.0 (12.6 to 13.4) |
| 30–39 | 10.32 (9.71 to 10.97) | 5.5 (5.0 to 6.0) | 13.9 (13.2 to 14.6) |
| 40+ | 11.97 (9.92 to 14.36) | 7.0 (5.3 to 9.1) | 15.9 (13.6 to 18.5) |
| Maternal education | |||
| Elementary | 11.63 (10.21 to 13.21) | 6.3 (5.1 to 7.7) | 18.8 (17.1 to 20.7) |
| Middle | 12.32 (11.59 to 13.10) | 7.0 (6.4 to 7.7) | 17.7 (16.8 to 18.6) |
| High school | 10.72 (10.41 to 11.04) | 6.0 (5.7 to 7.7) | 14.5 (14.1 to 14.8) |
| College+ | 6.07 (5.50 to 6.70) | 3.1 (2.6 to 3.5) | 7.5 (6.9 to 8.2) |
| Maternal marital status | |||
| Single | 14.20 (13.44 to 14.99) | 7.9 (7.3 to 8.7) | 20.7 (19.8 to 21.6) |
| Married | 9.60 (9.32 to 9.90) | 5.2 (5.0 to 5.4) | 12.9 (12.6 to 13.3) |
| Other | 11.60 (10.75 to 12.50) | 6.7 (6.0 to 7.5) | 15.6 (14.6 to 16.6) |
| Prenatal visits | |||
| 1–4 | 20.99 (20.17 to 21.83) | 8.7 (8.0 to 9.4) | 33.8 (32.8 to 34.8) |
| 5–9 | 11.50 (11.08 to 11.93) | 6.8 (6.4 to 7.2) | 16.2 (15.8 to 16.7) |
| 10–14 | 5.02 (4.70 to 5.35) | 4.1 (3.8 to 4.4) | 3.7 (3.4 to 4.0) |
| 15–19 | 3.79 (3.20 to 4.47) | 2.8 (2.3 to 3.4) | 2.7 (2.2 to 3.3) |
| 20+ | 11.95 (9.25 to 15.28) | 7.4 (5.0 to 10.9) | 27.5 (23.6 to 31.8) |
| Parity | |||
| 0 | 12.84 (10.99 to 14.94) | 6.7 (5.3 to 8.5) | 12.9 (11.1 to 15.0) |
| 1–2 | 9.97 (9.57 to 10.39) | 5.2 (4.9 to 5.6) | 13.8 (13.3 to 14.3) |
| 3–4 | 10.39 (9.80 to 11.01) | 5.7 (5.2 to 6.2) | 14.7 (14.1 to 15.4) |
| 5+ | 10.92 (10.17 to 11.72) | 5.4 (4.8 to 6.0) | 17.9 (16.9 to 18.8) |
| No previous pregnancy | 10.86 (10.37 to 11.38) | 6.5 (6.1 to 6.9) | 13.4 (12.9 to 14.0) |
| Cigarettes per day | |||
| None | 8.13 (7.81 to 8.46) | 13.6 (13.2 to 14.0) | 4.1 (3.9 to 4.4) |
| 1–4 | 10.94 (10.19 to 11.73) | 16.5 (15.6 to 17.4) | 5.6 (5.0 to 6.2) |
| 5–9 | 13.19 (12.15 to 14.31) | 16.5 (15.3 to 17.7) | 7.7 (6.8 to 8.7) |
| 10–14 | 14.45 (13.48 to 15.48) | 15.3 (14.3 to 16.3) | 8.6 (7.7 to 9.5) |
| 15–19 | 12.39 (10.29 to 14.02) | 13.1 (11.6 to 14.8) | 7.1 (5.9 to 8.5) |
| 20+ | 14.23 (13.47 to 15.03) | 13.6 (12.9 to 14.4) | 8.6 (8.0 to 9.3) |
| Infant gender | |||
| Male | 9.34 (9.00 to 9.70) | 4.6 (4.3 to 4.8) | 14.7 (14.3 to 15.2) |
| Female | 11.66 (11.28 to 13.47) | 6.9 (6.6 to 7.3) | 13.9 (13.5 to 14.3) |
| Previous abortions | |||
| No previous pregnancy | 10.94 (10.44 to 11.45) | 6.5 (6.1 to 7.0) | 13.5 (12.9 to 14.0) |
| 0 | 6.69 (6.41 to 6.98) | 3.5 (3.3 to 3.7) | 11.9 (11.5 to 12.3) |
| 1 | 18.22 (17.26 to 19.21) | 10.2 (9.3 to 11.1) | 21.4 (20.4 to 22.5) |
| 2 | 26.37 (24.36 to 28.47) | 16.9 (14.9 to 19.0) | 24.6 (22.7 to 26.7) |
| 3+ | 38.45 (35.40 to 41.59) | 24.0 (20.8 to 27.6) | 35.4 (32.4 to 38.5) |
CI, Confidence interval; LBW, low birth weight; PB, preterm birth; TLBW, term low birth weight.