Table 1 Demographics of the INSIGHT cohort study population (all and by risk status).
Characteristic | Sub-category | High-risk women N = 405 | Low-risk women N = 214 | Comparison (difference/risk ratio, 95% CI)* | All women N = 619 |
|---|---|---|---|---|---|
Mean maternal age at booking, years (SD) | 32.7 (5.1) | 32.5 (4.7) | 0.19 (-0.62–0.99) | 32.6 (5.0) | |
Ethnic group N (%) | White European | 246 (60.7) | 162 (75.7) | Ref | 408 (67.0) |
Black African/Caribbean | 114 (28.1) | 29 (13.6) | 2.09 (1.44–3.01) | 143 (23.1) | |
Asian | 37 (9.1) | 14 (6.5) | 1.89 (0.87–4.11) | 51 (8.20 | |
Other | 8 (2.0) | 9 (4.2) | 0.93 (0.49–1.75 | 17 (2.7) | |
Risk factor N (%) | Previous spontaneous preterm birth | 177 (43.7) | – | – | – |
Previous late miscarriage | 138 (34.0) | – | – | – | |
Previous PPROM | 111 (27.4) | – | – | – | |
Previous cervical surgery | 143 (35.3) | – | – | – | |
Incidental finding of a short cervix < 25 mm | 4 (0.99) | – | – | – | |
Smoking status N (%) | Never smoked | 283 (69.9) | 171 (79.9) | Ref | 454 (73.3) |
Current smoker | 22 (5.4) | 6 (2.8) | 2.13 (0.88–5.15) | 28 (4.5) | |
Ex-smoker (gave up in current pregnancy) | 29 (7.2) | 11 (5.1) | 1.54 (0.79–3.00) | 40 (6.5) | |
Ex (gave up before current pregnancy | 69 (17.0) | 26 (12.1) | 1.49 (0.98–2.25) | 95 (15.3) | |
Unknown | 2 (0.5) | 0 (0) | |||
Mean BMI at booking kg/m2 (SD) | 26.6 (6.9) | 24.7 (4.6) | 1.90 (0.98–2.81) | 25.9 (6.2) | |
Current or past history of domestic violence N (%) | 19 (4.7) | 1 (0.5) | 10.31 (1.39–76.45) | 20 (3.2) | |
Current or past history of recreational drug use N (%) | 11 (2.7) | 7 (3.3) | 0.83 (0.33–2.12) | 18 (2.9) | |
Pregnancy outcome N (%) | Term delivery > 37 weeks | 310 (77.1) | 200 (95.7) | 0.81 (0.76–0.98) | 510 (82.4) |
Iatrogenic preterm delivery < 37 weeks | 17 (4.2) | 4 (1.9) | 2.21 (0.75–6.48) | 21 (3.4) | |
Spontaneous preterm delivery < 37 weeks | 75 (18.7) | 5 (2.4) | 7.80 (3.20–18.98) | 80 (13.1) | |
Spontaneous preterm delivery < 34 weeks | 40 (10.0) | 1 (0.4) | 20.80 (2.88–150.21) | 41 (6.7) | |
Late miscarriage | 14 (3.5) | 0 (0) | – | 14 (2.3) | |
Premature pre-labour rupture of membranes | 42 (10.4) | 5 (2.3) | 4.37 (1.75–10.87) | 47(7.6) | |
Cervical shortening < 25 mm < 24 weeks in current pregnancy N (%) | 71 (17.5) | Not measured | – | – | |
Received prophylactic or emergency intervention to prevent preterm birth N (%) | Abdominal or vaginal cerclage | 105 (25.9) | 0 (0) | ** | 105 (17.0) |
Progesterone beyond 14 weeks’ gestation | 26 (6.4) | 0 (0) | ** | 26 (4.2) | |
Arabin pessary | 6 (1.5) | 0 (0) | ** | 6 (1.0) |
