Table 1. Baseline characteristics of pregnancies in the study epochs before and after the introduction of universal 36-week ultrasound scan.
| Variables | Before universal 36-week scan (n = 16,777) | After universal 36-week scan (n = 7,351) | P value |
|---|---|---|---|
| Maternal age in years | 33.2 ± 5.18 | 35.7 ± 5.39 | <0.001 |
| BMI, kg/m2 | 25.6 ± 5.35 | 25.7 ± 5.36 | 0.194 |
| Parous, n (%) | 8,316 (49.6) | 3,617 (49.2) | 0.612 |
| Ethnicity, n (%) | |||
| Caucasian | 8,014 (47.8) | 3,463 (47.1) | 0.353 |
| BAME | 6,588 (39.3) | 2,785 (37.9) | 0.044 |
| Not stated | 2,175 (12.9) | 1,103 (15.0) | <0.001 |
| IMD quintile, n (%) | |||
| First | 1,056 (6.3) | 423 (5.8) | 0.114 |
| Second | 4,323 (25.8) | 1,874 (25.5) | 0.665 |
| Third | 4,989 (29.7) | 2,278 (31.0) | 0.052 |
| Fourth | 3,740 (22.3) | 1,664 (22.6) | 0.566 |
| Fifth | 2,626 (15.6) | 1,087 (14.8) | 0.090 |
| Missing | 43 (0.3) | 25 (0.3) | 0.318 |
| All breech presentations, n (%) | 578 (3.4) | 251 (3.4) | 0.953 |
| Gestational age at delivery in weeks | 39.8 ± 1.13 | 39.9 ± 1.18 | <0.001 |
| Mode of birth, n (%) | |||
| Elective cesarean | 2,019 (12.0) | 959 (13.0) | 0.029 |
| Emergency cesarean | 2,169 (12.9) | 845 (11.5) | 0.002 |
| Vaginal breech, any | 49 (0.29) | 15 (0.20) | 0.276 |
| Vaginal vertex, spontaneous | 9,606 (57.3) | 4,383 (59.6) | <0.001 |
| Vaginal vertex, operative | 2,934 (17.5) | 1,149 (15.6) | <0.001 |
Comparison between the 2 groups was performed using Wilcoxon-signed rank test, t test (for continuous variables), or chi-squared test (for binary or categorical variables), where appropriate.
BAME, black, Asian, and minority ethnic; BMI, body mass index; IMD, index of multiple deprivation.