Table 2.
Demographics of the INSIGHT cohort study population by outcome (*preterm iatrogenic deliveries excluded n = 21).
| Characteristic | Sub-category | sPTB < 37 N = 80 |
Term delivery N = 510 |
Comparison (difference/risk ratio, 95% CI)* |
|---|---|---|---|---|
| Mean maternal age at booking in years (SD) | 32.7 (6.3) | 32.6 (4.7) | 0.08 (− 1.36 to 1.52) | |
| Ethnic group N (%) | White European | 37 (46.3) | 354 (69.4) | Ref |
| Black African/Caribbean | 27 (33.8) | 107 (21.0) | 1.82 (1.30 to 2.53) | |
| Asian | 10 (12.5) | 21 (4.1) | 3.80 (1.91 to 7.57) | |
| Other | 16 (20.0) | 49 (9.6) | 1.90 (0.84 to 4.34) | |
| Risk factor N (%) | Previous spontaneous preterm birth | 36 (45.0) | 131 (25.7) | 1.75 (1.32 to 2.33) |
| Previous late miscarriage | 37 (46.3) | 93 (18.2) | 2.54 (1.88 to 3.42) | |
| Previous PPROM | 20 (25.0) | 84 (16.5) | 1.52 (0.99 to 2.33) | |
| Previous cervical surgery | 14 (17.5) | 124 (24.3) | 0.72 (0.44 to 1.19) | |
| Incidental finding of a short cervix < 25 mm | 0 (0) | 2 (0.4) | – | |
| Smoking status N (%) | Never smoked | 62 (77.5) | 369 (72.4) | Ref |
| Current smoker | 3 (3.8) | 24 (4.7) | 0.76 (0.23 to 2.44) | |
| Ex-smoker (gave up in current pregnancy) | 3 (3.8) | 36 (7.1) | 0.52 (0.16 to 1.64) | |
| Ex (gave up before current pregnancy | 12 (15.0) | 79 (15.6) | 0.92 (0.53 to 1.60) | |
| Unknown | 0 (0) | 2 | – | |
| Mean BMI at booking in kg/m2 (SD) | 26.7 (5.0) | 25.74 (6.5) | 0.98 (− 0.24 to 2.19) | |
| Received prophylactic or emergency intervention to prevent preterm birth N (%) | Abdominal or vaginal cerclage | 33 (41.3) | 69 (13.5) | – |
| Progesterone beyond 14 weeks of gestation | 12 (15.0) | 13 (2.5) | – | |
| Arabin pessary | 4 (5.0) | 3 (0.6) | – |
*Quantitative variables analysed by regression with robust standard errors. Categorical variables analysed with X2 test.