Table 1. Clinical characteristics of preterm delivery cases and controls*.
| Variable | Cases | Controls | p-value |
| n = 240 | n = 439 | ||
| Entry to care | |||
| Age (yr) | 22.82±5.93 | 22.10±5.20 | 0.23 |
| BMI (kg/m2) | 26.25±6.42 | 25.59±5.72 | 0.43 |
| Obesity (BMI ≥30) n (%) | 57 (23.75) | 81 (18.45) | 0.11 |
| Nulliparas n (%) | 86 (35.83) | 175 (39.86) | 0.30 |
| Cigarette smoking n (%) | 55 (22.92) | 83 (18.91) | 0.21 |
| Ethnicity n (%) | |||
| Hispanic | 105 (43.75) | 212 (48.29) | |
| African American | 100 (41.67) | 149 (33.94) | |
| Caucasian and other | 35 (14.58) | 78 (17.77) | 0.13 |
| Medicaid n (%) | 238 (99.16) | 427 (97.27) | 0.24 |
| Gestational age at entry (weeks) | 14.10±4.80 | 14.21±4.91 | 0.79 |
| Prior history of preterm delivery n (%)† | 37 (24.03) | 27 (10.23) | 0.0002 |
| Blood pressure | |||
| Systolic blood pressure | 112.90±13.60 | 111.80±11.5 | 0.20 |
| Diastolic blood pressure | 70.12±9.70 | 69.98±8.70 | 0.93 |
| 3rd trimester and birth outcome | |||
| Blood pressure | |||
| Systolic blood pressure | 119.83±15,41 | 115.50±10.93 | <0.001 |
| Diastolic blood pressure | 76.43±12.90 | 72.20±9.02 | <0.001 |
| Singleton n (%) | 228 (95.00) | 438 (99.77) | <0.001 |
| Gestational diabetes mellitus n (%) | 14 (5.83) | 38 (8.65) | 0.249 |
| Preeclampsia n (%) | 47 (19.58) | 39 (8.88) | <0.0001 |
| Gestational age at delivery (weeks) | 33.14±3.91 | 39.24±1.21 | <0.0001 |
| Infant birth weight (g) | 2178±825 | 3330±435 | <0.0001 |
*Data are mean ± SD or n (%). p-values are from ANOVA or chi-square test.
†
Prior history of preterm delivery in parous women.