Table 1. Characteristics of study population.
| Measure | Number with data | Preterm (<37 weeks)(n = 775) | Term (37–42 weeks) (n = 11811) | P |
|---|---|---|---|---|
| Pre-pregnancy factors | ||||
| Maternal age | 12,586 | 27.5 (4.9) | 27.9 (5.0) | 0.0247 |
| Maternal socioeconomic group | 9,052 | 0.930 | ||
| I–Professional | 22 (4.3%) | 460 (5.5%) | ||
| Ii–Managerial | 158 (31.0%) | 2,610 (31.0%) | ||
| iiiN–Skilled non-manual | 41 (8.1%) | 685 (8.0%) | ||
| iiiM–Skilled manual | 228 (44.8%) | 3729 (43.7%) | ||
| iv—Semi-skilled | 49 (9.6%) | 863 (10.1%) | ||
| v–Unskilled | 11 (2.2%) | 196 (2.3%) | ||
| Mother’s highest educational qualification* | 11,175 | 0.005 | ||
| CSE | 170 (26.4%) | 2,182 (20.7%) | ||
| Vocational | 70 (10.9%) | 1,079 (10.2%) | ||
| O Level | 205 (31.9%) | 3730 (35.4%) | ||
| A Level | 137 (21.3%) | 2,291 (21.8%) | ||
| Degree | 61 (9.5%) | 1,250 (11.9%) | ||
| Non-white ethnicity | 66 (9.3%) | 488 (4.5%) | <0.001 | |
| Antenatal and intrapartum factors | ||||
| Primiparous | 11,632 | 348 (48.7%) | 4,804 (44.0%) | 0.227 |
| Maternal Hypertension | 12,585 | 105 (13.6%) | 406 (3.4%) | <0.001 |
| Multiple birth | 12,586 | 149 (19.2%) | 186 (1.6%) | <0.001 |
| Delivery | 11,465 | <0.001 | ||
| Spontaneous cephalic | 427 (58.3%) | 8,191 (76.3%) | ||
| Emergency caesarean section | 166 (22.7%) | 624 (5.8%) | ||
| Elective caesarean section | 40 (5.5%) | 449 (4.2%) | ||
| Instrumental | 62 (8.5%) | 1323 (12.3%) | ||
| Breech | 37 (5.1%) | 146 (1.4%) | ||
| Infant and post-partum factors | ||||
| Male | 12,586 | 443 (57.2%) | 6033 (51.1%) | 0.001 |
| Birth Weight (g) | 12441 | 2347 (615) | 3456 (485) | <0.001 |
| Birth Length (cm) | 9518 | 47.0 (2.6) | 50.8 (2.3) | <0.001 |
| Head Circumference (cm) | 9664 | 32.4 (2.1) | 34.9 (1.4) | <0.001 |
| Apgar at 1 minute | 11,467 | 9 (7–9) | 9 (8–9) | <0.001 |
| Apgar at 5 minute | 11,467 | 9 (9–10) | 10 (9–10) | <0.001 |
| Received resuscitation | 11,452 | 182 (24.9%) | 838 (7.8%) | <0.001 |
Standard deviations are given for means of normally distributed continuous variables and percentages for proportions.
* CSE = Certificate in Secondary Education (commonly taken at 16 years of age); Vocational = City & Guilds (intermediate level), technical, shorthand or typing, or other qualification; O level = Ordinary level (commonly taken at 16 years of age); A level = Advanced level (commonly taken at 18 years of age), state enrolled nurse, state registered nurse, City & Guilds (final or full level) or teaching qualification; Degree = University degree