Table 1 Population characteristics of the 1330 women enrolled in the Boston Birth Cohort, stratified by preterm delivery subgroups
Variables | Term delivery | Preterm delivery (PTD) subgroupsa | ||
|---|---|---|---|---|
mPTD + preeclampsia | mPTD only | sPTD | ||
N | 980 | 79 | 52 | 219 |
Maternal age (years), M ± SD | 28.1 ± 6.6 | 31.1 ± 6.5** | 30.2 ± 7.2 | 28.6 ± 6.4 |
Ethnicity | ||||
African American | 621 (63.4) | 61 (77.2) | 27 (51.9) | 148 (67.6) |
White | 40 (4.1) | 2 (2.5) | 2 (3.9) | 12 (5.5) |
Hispanic | 200 (20.4) | 12 (15.2) | 17 (32.7) | 45 (20.5) |
Others | 119 (12.1) | 4 (5.1) | 6 (11.5) | 14 (6.4) |
Maternal birthplace: non-US-born | 620 (63.3) | 50 (63.3) | 33 (63.5) | 115 (52.5)** |
Married | 338 (34.5) | 26 (32.9) | 17 (32.7) | 54 (24.7)* |
Pregestational BMI (kg/m2) category | ||||
Normal | 470 (48.0) | 21 (26.6)** | 16 (30.8) | 104 (47.5) |
Overweight | 258 (26.3) | 24 (30.4) | 17 (32.7) | 62 (28.3) |
Obese | 208 (21.2) | 32 (40.5) | 16 (30.8) | 43 (19.6) |
Unknown | 44 (4.5) | 2 (2.5) | 3 (5.8) | 10 (4.6) |
Highest education level | ||||
< High school | 273 (27.9) | 12 (15.2) | 21 (40.4) | 62 (28.3) |
High school | 362 (36.9) | 39 (49.4) | 18 (34.6) | 86 (39.3) |
College or above | 340 (34.7) | 28 (35.4) | 13 (25.0) | 70 (32.0) |
Missing | 5 (0.5) | 0 (0.0) | 0 (0.0) | 1 (0.5) |
Nulliparity | 430 (43.9) | 34 (43.0) | 17 (32.7) | 97 (44.3) |
Maternal smoking during pregnancy | ||||
Never | 840 (85.7) | 62 (78.5) | 41 (78.8) | 161 (73.5)*** |
Quitter | 64 (6.5) | 8 (10.1) | 3 (5.8) | 20 (9.1) |
Current | 64 (6.5) | 8 (10.1) | 8 (15.4) | 38 (17.4) |
Unknown | 12 (1.2) | 1 (1.3) | 0 (0.0) | 0 (0.0) |
Alcohol drinking during pregnancy | 73 (7.4) | 3 (3.8) | 5 (9.6) | 20 (9.1) |
Stress during lifetime | ||||
Mild | 410 (41.8) | 29 (36.7)* | 16 (30.8) | 76 (34.7) |
Average | 490 (50.0) | 36 (45.6) | 30 (57.7) | 118 (53.9) |
Stressful | 80 (8.2) | 14 (17.7) | 6 (11.5) | 25 (11.4) |
Chronic hypertension | 37 (3.8) | 28 (35.9)*** | 6 (11.5)* | 12 (5.5) |
Gestational diabetes | 69 (7.0) | 9 (11.4) | 4 (7.7) | 16 (7.3) |
Pregestational diabetes | 37 (3.8) | 12 (15.2)*** | 4 (7.7) | 12 (5.5) |
Illicit drug use during pregnancy | 66 (6.7) | 9 (11.4) | 6 (11.5) | 34 (15.5)*** |
Mode of delivery, c-section | 311 (31.8) | 52 (65.8)*** | 42 (80.8)*** | 65 (29.7) |
Infant’s sex, male | 497 (50.7) | 30 (38.0)* | 31 (59.6) | 123 (56.2) |