Table I.
Baseline characteristics of the subjects for the analysis of blood pressure during pregnancy and preterm birth. All deliveries are considered.
| Term Birth (≥ 37 wks) (N = 4804) | Late Preterm Birth (34 – 36 wks) (N = 289) | Early Preterm Birth (<34 wks) (N = 74) | p value* | ||
|---|---|---|---|---|---|
| Age | 23.3 (4.4) | 22.1 (4.2) | 21.7 (3.8) | <.0001 | |
| Education (years in school) | 10 (3.3) | 9.9 (3.8) | 9.8 (3.5) | .60 | |
| Body mass index, kg/m² | 21.5 (4.0) | 21.7 (4.2) | 22.2 (4.3) | .16 | |
| Gestational age at admission | 15.8 (3.2) | 15.1 (3.3) | 16.3 (2.7) | .0007 | |
| Gravidity | 1 | 4165 (92.8%) | 262 (5.8%) | 64 (1.4%) | .15 |
| 2+ | 639 (94.5%) | 27 (4.0%) | 10 (1.5%) | ||
| Smoker | Yes | 198 (94.3%) | 9 (4.3%) | 3 (1.4%) | .71 |
| No | 4603 (93.0%) | 279 (5.6%) | 70 (1.4%) | ||
| Race | European | 1083 (93.6%) | 61 (5.3%) | 13 (1.1%) | <.0001 |
| Indian | 1387 (91.8%) | 108 (7.1%) | 16 (1.1%) | ||
| African | 602 (85.5%) | 72 (10.2%) | 30 (4.3%) | ||
| Middle Eastern | 289 (88.4%) | 29 (8.9%) | 9 (2.7%) | ||
| South East Asian | 1443 (98.3%) | 19 (1.3%) | 6 (0.4%) | ||
| Calcium treatment | Yes | 2422 (93.4%) | 143 (5.5%) | 29 (1.1%) | 0.15 |
| No | 2382 (92.6%) | 146 (5.6%) | 45 (1.8%) | ||
| Onset of labor | Spontaneous | 4199 (93.8%) | 229 (5.1%) | 51 (1.1%) | <.0001 |
| Induced | 457 (91.0%) | 35 (7.0%) | 10 (2.0%) | ||
| Elective caesarean delivery | 144 (79.5%) | 24 (13.3%) | 13 (7.2%) | ||
*
Analysis of variance test for continuous variables and Chi-square test for categorical variables.