Sample characteristics and descriptive statistics by cohort
| NSHD | NCDS | BCS | |||||||
| Mean/count | SD/% | 95% CI | Mean/count | SD/% | 95% CI | Mean/count | SD/% | 95% CI | |
| Covariates | |||||||||
| Sex | |||||||||
| Male | 1151 | 50.42 | 48.3 to 52.4 | 4614 | 49.16 | 48.1 to 50.2 | 3646 | 47.78 | 46.7 to 48.9 |
| Female | 1132 | 49.58 | 47.5 to 51.7 | 4771 | 50.84 | 49.8 to 51.9 | 3985 | 52.22 | 51.1 to 53.3 |
| Birth weight (grams) | 3397.3 | 505.56 | 3376.5 to 3418 | 3335.69 | 499.81 | 3325.6 to 3345.8 | 3315.29 | 517.17 | 3303.7 to 3326.9 |
| Breastfed | |||||||||
| Never | 488 | 21.38 | 19.7 to 23.1 | 2608 | 27.79 | 26.9 to 28.7 | 4706 | 61.67 | 60.6 to 62.8 |
| Ever | 1795 | 78.62 | 76.9 to 80.3 | 6777 | 72.21 | 71.3 to 73.1 | 2925 | 38.33 | 37.2 to 39.4 |
| Early life SEP | |||||||||
| SEP (childhood) | |||||||||
| I | 160 | 7.01 | 6 to 8.1 | 432 | 4.6 | 4.2 to 5 | 397 | 5.2 | 4.7 to 5.7 |
| II | 462 | 20.24 | 18.6 to 21.9 | 2053 | 21.9 | 21 to 22.7 | 2058 | 27 | 26 to 29 |
| III.1 | 336 | 14.72 | 13.3 to 16.2 | 927 | 9.9 | 9.3 to 10.4 | 749 | 9.8 | 9.2 to 10.5 |
| III.2 | 783 | 34.3 | 32.3 to 36.3 | 4101 | 43.7 | 42.7 to 44.7 | 3196 | 41.9 | 40.8 to 43 |
| IV | 430 | 18.83 | 17.2 to 20.5 | 1198 | 12.8 | 12.1 to 13.4 | 862 | 11.3 | 10.6 to 12 |
| V | 112 | 4.91 | 4.1 to 5.9 | 674 | 7.2 | 6.7 to 7.7 | 369 | 4.8 | 4.4 to 5.3 |
| Paternal education | |||||||||
| Compulsory | 1534 | 67.2 | 65.2 to 69.1 | 6851 | 73 | 72.1 to 73.9 | 4686 | 61.4 | 60.7 to 62.9 |
| Postcompulsory | 749 | 32.8 | 30.9 to 34.8 | 2534 | 27 | 26.1 to 27.9 | 2945 | 38.6 | 37.4 to 39.7 |
| Maternal education | |||||||||
| Compulsory | 1608 | 70.4 | 68.5 to 72.3 | 6824 | 72.7 | 71.8 to 73.6 | 4718 | 61.8 | 60.7 to 62.9 |
| Postcompulsory | 675 | 29.6 | 27.7 to 31.4 | 2561 | 27.3 | 26.4 to 28.2 | 2913 | 38.2 | 37.1 to 39.3 |
| Cognitive ability age 10/11 | |||||||||
| Verbal reasoning | 30.67 | 10.61 | 30.2 to 31.1 | 29.46 | 10.78 | 29.2 to 29.7 | 29.57 | 5.57 | 29.4 to 29.7 |
| Non-verbal reasoning | 28.15 | 8.69 | 27.8 to 28.5 | 27.61 | 8.65 | 27.4 to 27.8 | 29.04 | 8.59 | 28.8 to 29.2 |
| Mathematics | 27.49 | 10.89 | 27 to 27.9 | 22.65 | 12.24 | 22.4 to 22.9 | 31.91 | 7.62 | 31.7 to 32.1 |
| Reading | 30.64 | 6.84 | 30.4 to 30.9 | 23.98 | 8.23 | 23.8 to 24.1 | 31.35 | 4.86 | 31.2 to 41.5 |
| Education | |||||||||
| None | 814 | 35.7 | 33.7 to 37.7 | 1124 | 12 | 11.3 to 12.7 | 817 | 10.7 | 10 to 11.4 |
| NVQ level 1 | 163 | 7.1 | 6.1 to 8.3 | 1376 | 14.7 | 14 to 15.4 | 592 | 7.8 | 14 to 15.4 |
| NVQ level 2 | 476 | 20.8 | 19.2 to 22.6 | 2761 | 29.4 | 28.5 to 30.4 | 2412 | 31.6 | 30.6 to 32.7 |
| NVQ level 3 | 604 | 26.5 | 24.7 to 28.3 | 1392 | 14.8 | 14.1 to 15.6 | 986 | 12.9 | 12.2 to 13.7 |
| NVQ level 4/5 | 226 | 9.9 | 8.7 to 11.2 | 2732 | 29.1 | 28.2 to 30 | 2824 | 37 | 35.9 to 38.1 |
| Mid-life occupation | |||||||||
| I | 136 | 6 | 5 to 7 | 461 | 4.9 | 4.5 to 5.4 | 409 | 5.4 | 4.9 to 5.9 |
| II | 855 | 37.5 | 35.5 to 39.5 | 3382 | 36 | 35.1 to 37 | 3270 | 42.9 | 41.7 to 44 |
| III.1 | 544 | 23.8 | 22.1 to 25.6 | 2135 | 22.7 | 21.9 to 23.6 | 1495 | 19.6 | 18.7 to 20.5 |
| III.2 | 412 | 18 | 16.4 to 19.7 | 1873 | 20 | 19.2 to 20.8 | 1320 | 17.3 | 16.4 to 18.2 |
| IV | 255 | 11.2 | 9.9 to 12.5 | 1246 | 13.3 | 12.6 to 14 | 1019 | 13.4 | 12.6 to 14.1 |
| V | 81 | 3.5 | 2.8 to 4.4 | 288 | 3.1 | 2.7 to 3.4 | 118 | 1.5 | 1.3 to 1.8 |
| Mid-life cognitive ability | |||||||||
| Animal naming | 23.82 | 6.63 | 23.6 to 24.1 | 22.30 | 6.26 | 22.2 to 22.4 | 23.65 | 6.14 | 23.5 to 23.8 |
| Processing speed | 280.19 | 75.53 | 277.1 to 283.3 | 333.97 | 88.81 | 332.2 to 335.8 | 346.29 | 84.38 | 344.4 to 348.2 |
| Immediate recall | 5.79 | 1.99 | 5.7 to 5.9 | 6.55 | 1.47 | 6.5 to 6.6 | 6.64 | 1.43 | 6.6 to 6.7 |
| Delayed recall | 8.00 | 2.05 | 7.9 to 8.1 | 5.42 | 1.83 | 5.4 to 5.5 | 5.49 | 1.8 | 5.4 to 5.5 |
Data are from imputed sample (n=2283 in NSHD, n=9385 in NCDS and n=7631 in BCS70). Summary statistics for unimputed samples available in online supplemental materials table S3.
BCS, British Cohort Study; NCDS, National Child Development Study; NSHD, National Survey of Health and Development; NVQ, National Vocational Qualification; SEP, socioeconomic position.