Table 1.
Number (percent) of subjects in each outcome group by demographic characteristics and crude odds ratios [95% CI]
| Parameter | Preterm birth (N = 1,027) n (column %) | Term normal weight (N = 1,282) n (column %) | Preterm crude OR [95% CI] |
|---|---|---|---|
| Maternal age (years) | |||
| <20 | 120 (11.7) | 120 (9.4) | 1.21 [0.89, 1.65] |
| 20–24 (reference) | 222 (21.6) | 268 (20.9) | 1.0 |
| 25–29 | 239 (23.3) | 373 (29.1) | 0.78 [0.61, 0.99] |
| 30–34 | 259 (25.2) | 338 (26.4) | 0.93 [0.73, 1.18] |
| 35+ | 187 (18.2) | 183 (14.3) | 1.23 [0.94, 1.62] |
| (p < 0.01) | |||
| Maternal race/ethnicity | |||
| Non-Hispanic White (reference) | 149 (14.5) | 252 (19.7) | 1.0 |
| Latina | 711 (69.2) | 842 (65.7) | 1.43 [1.14, 1.79] |
| Black | 87 (8.5) | 73 (5.7) | 2.02 [1.39, 2.92] |
| Asiana or otherb | 75 (7.3) | 107 (8.4) | 1.19 [0.83, 1.70] |
| Missing | 5 (0.5) | 8 (0.6) | |
| (p < 0.01) | |||
| Maternal education (years) | |||
| ≤8 | 143 (13.9) | 161 (12.6) | 0.99 [0.75, 1.30] |
| 9–11 | 225 (21.9) | 266 (20.8) | 0.94 [0.74, 1.19] |
| 12 (reference) | 298 (29.0) | 332 (25.9) | 1.0 |
| 13–15 | 162 (15.8) | 192 (15.0) | 0.94 [0.72, 1.22] |
| 16+ | 307 (24.0) | 185 (18.0) | 0.67 [0.53, 0.85] |
| Missing | 24 (1.9) | 14 (1.4) | |
| (p = 0.01) | |||
| Parity | |||
| ≥1 | 635 (61.8) | 769 (60.0) | 1.08 [0.92, 1.28] |
| 0 (reference) | 392 (38.2) | 513 (40.0) | 1.0 |
| (p = 0.37) | |||
| Household income | |||
| <$40,000/year | 635 (61.8) | 746 (58.2) | 1.29 [1.05, 1.57] |
| ≥$40,000/year (reference) | 224 (21.8) | 338 (26.4) | 1.0 |
| Missing | 168 (16.4) | 198 (15.4) | |
| (p = 0.01) | |||
| Mother’s marital status | |||
| Married (reference) | 534 (52.3) | 755 (59.2) | 1.0 |
| Living with partner | 272 (26.6) | 266 (20.9) | 1.45 [1.18, 1.77] |
| Single, divorced, separated | 215 (20.9) | 254 (19.8) | 1.20 [0.97, 1.48] |
| Missing | 6 (0.6) | 7 (0.6) | |
| (p < 0.01) | |||
| Mother’s birthplace | |||
| US-born (reference) | 416 (40.5) | 534 (41.7) | 1.0 |
| Foreign-born | 609 (59.3) | 748 (58.4) | 1.05 [0.88, 1.24] |
| Missing | 2 (0.2) | 0 (0.0) | |
| (p = 0.60) | |||
| Smoking status | |||
| Non-smoker (reference) | 726 (70.7) | 875 (68.3) | 1.0 |
| Former smoker | 243 (23.7) | 349 (27.2) | 0.84 [0.69, 1.01] |
| Pregnancy smoker | 57 (5.6) | 56 (4.4) | 1.23 [0.84, 1.79] |
| Missing | 1 (0.1) | 2 (0.2) | |
| (p = 0.09) | |||
| Alcohol use during pregnancy | |||
| Yes | 90 (8.8) | 111 (8.7) | 1.02 [0.76, 1.36] |
| No (reference) | 935 (91.0) | 1170 (91.3) | 1.0 |
| Missing | 2 (0.2) | 1 (0.1) | |
| (p = 0.92) | |||
| Prenatal care | |||
| Began in 1st trimester (reference) | 915 (89.1) | 1196 (93.3) | 1.0 |
| Began after 1st trimester, or no prenatal care | 103 (10.1) | 79 (6.2) | 1.70 [1.26, 2.31] |
| Missing | 9 (0.9) | 7 (0.6) | |
| (p < 0.01) | |||
| Primary source of payment for prenatal care | |||
| Private insurance or self pay (reference) | 394 (38.4) | 557 (43.5) | 1.0 |
| Other insurance or no insurancec | 632 (61.5) | 722 (56.3) | 1.24 [1.05, 1.46] |
| Missing | 1 (0.1) | 3 (0.20) | |
| (p = 0.01) |
aIncludes Chinese, Japanese, Korean, Vietnamese, Cambodian, Thai, Laotian, Filipino, Indian, other Asian
bIncludes Native American, Eskimo, Aleut, Hawaiian, Guamanian, Samoan, Pacific Islanders, and others
cIncludes Medicaid, Medicare, Worker’s compensation, Title V, No charge, Medically indigent, Medi-Cal CPS Program, no prenatal care, and other government and non-government programs