Table 1.
Descriptive statistics for the SLS sample for both outcomes and covariates.
| Categorical variables |
Term births |
Preterm births |
||
|---|---|---|---|---|
| N | % | N | % | |
| Low birthweight (<2500 g) | ||||
| Yes | 457 | 2.09 | n/a | |
| No | 21,428 | 97.91 | n/a | |
| Prematurity | ||||
| Less than 32 weeks | n/a | 193 | 0.83 | |
| Between 32 and 36 weeks inclusive | n/a | 1,049 | 4.54 | |
| Greater than 36 weeks | n/a | 21,885 | 94.63 | |
| Social class | ||||
| Professional | 935 | 4.27 | 972 | 4.2 |
| Managerial and Technical | 5816 | 26.58 | 6092 | 26.34 |
| Skilled Non-manual | 7534 | 34.43 | 7,971 | 34.47 |
| Skilled Manual | 1857 | 8.49 | 1961 | 8.48 |
| Partly Skilled | 3,500 | 15.99 | 3741 | 16.18 |
| Unskilled | 934 | 4.27 | 993 | 4.29 |
| Armed Forces | <15 | <0.1 | <15 | <0.1 |
| Unemployed | 1302 | 5.95 | 1,390 | 6.01 |
| Parity | ||||
| Multiparous | 12,570 | 57.44 | 13,176 | 56.97 |
| Nulliparous | 9315 | 42.56 | 9951 | 43.03 |
| Smoker during pregnancy | ||||
| No | 16,712 | 76.36 | 17,548 | 75.88 |
| Yes | 5173 | 23.64 | 5579 | 24.12 |
| Ethnicity | ||||
| Non-South Asian | 21,614 | 98.76 | 22,843 | 98.77 |
| South Asian | 271 | 1.24 | 284 | 1.23 |
| Mothers age at delivery | ||||
| 17–18 | 546 | 2.49 | 579 | 2.5 |
| 19–23 | 3070 | 14.03 | 3257 | 14.08 |
| 24–28 | 5987 | 27.36 | 6322 | 27.34 |
| 29–33 | 7303 | 33.37 | 7711 | 33.34 |
| 34–38 | 4078 | 18.63 | 4291 | 18.55 |
| 39+ | 901 | 4.12 | 967 | 4.18 |
| Education | ||||
| None | 3008 | 13.74 | 13.95 | 13.95 |
| O’ grade, Standard grade or equivalent | 4922 | 22.49 | 5237 | 22.64 |
| Higher, ‘A’ level, AS level or equivalent | 1671 | 7.64 | 1768 | 7.64 |
| GSVQ/SVQ Level 1 or 2 or equivalent | 4179 | 19.1 | 4420 | 19.11 |
| GSVQ/SVQ Level 3, ONC, OND or equivalent | 1068 | 4.88 | 1128 | 4.88 |
| HNC, HND, SVQ Level 4 or 5 or equivalent | 2059 | 9.41 | 2150 | 9.3 |
| First degree or higher degree or equivalent | 1714 | 7.83 | 1786 | 7.72 |
| Professional Qualifications or equivalent | 3264 | 14.91 | 3412 | 14.75 |
| Season of birth | ||||
| Winter | 5094 | 23.28 | 5412 | 23.4 |
| Spring | 5539 | 25.31 | 5841 | 25.26 |
| Summer | 5624 | 25.7 | 5967 | 25.8 |
| Autumn | 5628 | 25.72 | 5907 | 25.54 |
| Lone mother | ||||
| No | 20,309 | 92.8 | 21,423 | 92.63 |
| Yes | 1576 | 7.2 | 1704 | 7.37 |
| Continuous variables | Mean | |||
| Birthweight (g) | 3481.22 | n/a | ||
| Crime Rate (Log scaled) | 6.00 | 6.00 | ||
| Estimated weekly wage (£) | 353.34 | 352.27 | ||
| Gestational age (weeks) | 39.68 | 39.37 | ||