Characteristic% or Mean (±SD) | SGA, n = 42,702 (3.1%) | Not SGA, n = 1,347,463 | p value |
---|---|---|---|
Pregravid BMIa | ≤0.001 | ||
≤24.9 | 72.8 | 66.9 | |
25–29.9 | 17.8 | 21.6 | |
≥30 | 9.4 | 11.5 | |
Non-smoking | 71.1 | 84.9 | ≤0.001 |
Quitted smoking | 4.5 | 3.5 | |
Smoking | 24.3 | 11.6 | |
Married or cohabiting | 93.7 | 95.9 | ≤0.001 |
Mean number of deliveries (±SD) | 0.71 (±1.22) | 1.04 (±1.35) | ≤0.001 |
Mean number of pregnancies (±SD) | 1.18 (±1.63) | 1.48 (±1.70) | ≤0.001 |
Mean number of miscarriages (±SD) | 0.26 (±0.65) | 0.26 (±0.61) | 0.72 |
Mean number of prior terminations (±SD) | 0.14 (±0.45) | 0.12 (±0.41) | ≤0.001 |
IVFb | 1.3 | 1.1 | 0.001 |
Anemia ≤ 100 g/l | 0.6 | 0.6 | 0.28 |
Prior Cesarean section | 7.6 | 8.4 | ≤0.001 |
Chorionic villus biopsy | 1.1 | 0.9 | ≤0.001 |
Amniocentesis | 3.9 | 2.7 | ≤0.001 |
Placenta previa | 0.3 | 0.2 | ≤0.001 |
Placental abruption | 0.6 | 0.2 | ≤0.001 |
Induction | 18.8 | 13.3 | ≤0.001 |
Congenital anomalies | 8.7 | 2.8 | ≤0.001 |
Socioeconomic status | |||
Upper white-collar worker | 5.5 | 6.7 | ≤0.001 |
Lower white-collar worker | 31.2 | 32.6 | |
Blue-collar worker | 15.9 | 13.6 | |
Other | 19.5 | 19.8 | |
Missing | 27.9 | 27.2 |