Table 1.
Questionnaire response rates by early life factors
| Male | Female | |||||||
| Number | Response rate (%) | Odds ratio | (95% CI) | Number | Response rate (%) | Odds ratio | (95% CI) | |
| Sex | ||||||||
| Male | 5,742 | 59.8 | 1.00 | |||||
| Female | 5,540 | 67.7 | 1.41 | (1.31 to 1.52) | ||||
| Birth weight (lbs) | ||||||||
| <6.5 | 1,118 | 58.7 | 1.00 | 1,451 | 65.0 | 1.00* | ||
| 6.5–7.5 | 1,874 | 588 | 1.00 | (0.86 to 1.17) | 2,061 | 68.3 | 1.16 | (1.01 to 1.34) |
| 7.5–8.5 | 1,809 | 60.7 | 1.09 | (0.93 to 1.27) | 1,480 | 69.6 | 1.23 | (1.06 to 1.44) |
| ≥8.5 | 929 | 61.0 | 1.10 | (0.92 to 1.32) | 539 | 68.3 | 1.16 | (0.94 to 1.43) |
| Missing† | 12 | 83.3 | 9 | 22.2 | ||||
| Mother's marital status at birth‡ | ||||||||
| Single/widowed/divorced | 175 | 52.0 | 1.00 | 190 | 50.5 | 1.00 | ||
| Married | 5,564 | 60.0 | 1.39 | (1.02 to 1.87) | 5,349 | 68.3 | 2.11 | (1.58 to 2.83) |
| Missing† | 3 | 66.7 | 1 | 0.0 | ||||
| Father's social class at birth | ||||||||
| Unemployed/disabled/deceased | 297 | 52.9 | 1.00* | 336 | 56.9 | 1.00* | ||
| IV/V | 1,765 | 55.9 | 1.13 | (0.88 to 1.45) | 1,633 | 63.4 | 1.32 | (1.04 to 1.67) |
| III Manual | 2,486 | 59.7 | 1.32 | (1.04 to 1.68) | 2,442 | 68.4 | 1.64 | (1.30 to 2.07) |
| III Non-manual | 633 | 65.9 | 1.72 | (1.30 to 2.29) | 613 | 73.9 | 2.15 | (1.62 to 2.86) |
| I/II | 561 | 69.2 | 2.00 | (1.49 to 2.68) | 515 | 77.9 | 2.67 | (1.96 to 3.63) |
| Missing† | 0 | 1 | 0.0 | |||||
| Father's social class in 1962 | ||||||||
| Unemployed/disabled/deceased | 341 | 46.6 | 1.00* | 357 | 53.5 | 1.00* | ||
| IV/V | 1,424 | 55.4 | 1.42 | (1.12 to 1.80) | 1,419 | 64.3 | 1.57 | (1.24 to 1.98) |
| III Manual | 2,419 | 60.0 | 1.72 | (1.36 to 2.16) | 2,291 | 68.0 | 1.84 | (1.47 to 2.31) |
| III Non-manual | 701 | 67.3 | 2.36 | (1.80 to 3.09) | 630 | 73.2 | 2.37 | (1.79 to 3.13) |
| I/II | 776 | 67.8 | 2.41 | (1.85 to 3.14) | 781 | 76.6 | 2.84 | (2.16 to 3.73) |
| Missing | 81 | 43.2 | 0.87 | (0.54 to 1.42) | 62 | 50.0 | 0.87 | (0.51 to 1.48) |
| Number of siblings in 1962 | ||||||||
| 5 or more | 1,041 | 50.4 | 1.00* | 946 | 59.2 | 1.00* | ||
| 4 | 938 | 57.7 | 1.34 | (1.12 to 1.60) | 942 | 65.2 | 1.29 | (1.07 to 1.56) |
| 3 | 1,424 | 61.5 | 1.57 | (1.34 to 1.85) | 1,420 | 70.9 | 1.67 | (1.41 to 1.99) |
| 2 | 1,749 | 64.2 | 1.76 | (1.50 to 2.06) | 1,677 | 71.3 | 1.71 | (1.45 to 2.03) |
| 1 | 545 | 64.6 | 1.79 | (1.45 to 2.22) | 510 | 68.8 | 1.52 | (1.21 to 1.91) |
| Missing | 45 | 35.6 | 0.54 | (0.29 to 1.00) | 45 | 53.3 | 0.79 | (0.44 to 1.42) |
| Height for age at 1st medical exam 1962 | ||||||||
| ≤-1 | 734 | 54.4 | 1.00* | 872 | 62.3 | 1.00* | ||
| -1 to 0 | 1,882 | 57.1 | 1.12 | (0.94 to 1.33) | 1,969 | 66.0 | 1.17 | (1.00 to 1.39) |
| 0 to 1 | 2,139 | 62.3 | 1.39 | (1.17 to 1.65) | 1,775 | 69.9 | 1.40 | (1.18 to 1.67) |
| ≥1 | 737 | 66.9 | 1.70 | (1.37 to 2.10) | 723 | 73.7 | 1.70 | (1.37 to 2.11) |
| Missing | 250 | 52.8 | 0.94 | (0.70 to 1.25) | 201 | 67.7 | 1.27 | (0.92 to 1.75) |
| Weight for age at 1st medical exam (SD) | ||||||||
| ≤-1 | 870 | 56.7 | 1.00* | 795 | 63.9 | 1.00* | ||
| -1 to 0 | 2,045 | 59.5 | 1.12 | (0.96 to 1.32) | 2,109 | 65.5 | 1.07 | (0.91 to 1.27) |
| 0 to 1 | 1,810 | 59.2 | 1.11 | (0.94 to 1.31) | 1,667 | 70.0 | 1.32 | (1.10 to 1.58) |
| ≥1 | 767 | 67.8 | 1.61 | (1.31 to 1.97) | 769 | 72.7 | 1.50 | (1.21 to 1.87) |
| Missing | 250 | 52.8 | 0.86 | (0.65 to 1.13) | 200 | 67.5 | 1.17 | (0.84 to 1.63) |
| Rutter B behavioral score | ||||||||
| 9+ | 595 | 47.4 | 1.00* | 320 | 57.2 | 1.00* | ||
| 3–8 | 1,736 | 56.2 | 1.42 | (1.18 to 1.72) | 1,448 | 61.5 | 1.19 | (0.93 to 1.53) |
| 1–2 | 1,517 | 63.8 | 1.96 | (1.61 to 2.38) | 1,637 | 69.6 | 1.72 | (1.34 to 2.20) |
| 0 | 1,720 | 65.7 | 2.13 | (1.75 to 2.58) | 1,990 | 73.3 | 2.06 | (1.61 to 2.63) |
| Missing | 174 | 44.3 | 0.88 | (0.63 to 1.24) | 145 | 54.5 | 0.90 | (0.60 to 1.33) |
* p < 0.05 for the score test for trend (missings were not included).
† We did not calculate odds ratio and 95% confidence interval due to small sample size.
‡ p < 0.05 for the interaction with sex tested by using likelihood ratio test in logistic regression.