Table 1.
Description of the study population by classes of maternal age. Analyses were restricted to those offspring included in the primary analyses of cause-specific mortality. Within each class of maternal age, continuous variables were summarised as means, binary variables as percentages. P values tested for heterogeneity in each variable between the classes of maternal age. They came from unadjusted linear or logistic regressions with robust standard errors clustered by the mother’s identity. Intelligence and non-cognitive ability were each recorded on a scale of 1-9.
| Person, variable | Mother’s age at offspring birth | P | N | |||||
|---|---|---|---|---|---|---|---|---|
| ≤19 | 20–24 | 25–29 | 30–34 | 35–39 | ≥ 40 | |||
| Mothers | ||||||||
| Age at offspring birth (years) | 18.6 | 22.6 | 27.3 | 32.1 | 37.0 | 42.0 | <0.001 | 5,204,433 |
| Non-manual worker | 34.4% | 39.1% | 46.2% | 40.9% | 29.0% | 17.6% | <0.001 | 4,590,785 |
| Completed secondary school | 9.0% | 13.3% | 22.3% | 24.3% | 20.9% | 15.2% | <0.001 | 3,921,575 |
| Alive when offspring 16 | 99.3% | 99.3% | 99.1% | 98.6% | 97.7% | 96.2% | <0.001 | 3,542,302 |
| Alive when offspring 40 | 93.6% | 92.8% | 90.5% | 85.3% | 76.1% | 61.3% | <0.001 | 2,147,035 |
| Fathers | ||||||||
| Age at offspring birth (years) | 23.2 | 26.6 | 30.6 | 34.9 | 39.4 | 44.1 | <0.001 | 5,204,433 |
| Non-manual worker | 50.8% | 59.6% | 66.6% | 63.8% | 54.5% | 41.9% | <0.001 | 3,685,070 |
| Completed secondary school | 15.9% | 23.7% | 34.0% | 35.7% | 31.3% | 24.1% | <0.001 | 3,766,998 |
| Alive when offspring 16 | 97.7% | 97.9% | 97.8% | 96.9% | 94.8% | 91.3% | <0.001 | 3,542,270 |
| Alive when offspring 40 | 84.4% | 82.7% | 77.8% | 66.5% | 50.7% | 33.6% | <0.001 | 2,147,003 |
| Offspring | ||||||||
| Non-manual worker | 35.7% | 42.6% | 48.0% | 51.1% | 50.4% | 47.2% | <0.001 | 3,048,381 |
| Completed secondary school | 41.2% | 52.1% | 60.7% | 59.7% | 53.4% | 44.8% | <0.001 | 5,159,950 |
| Male | 51.0% | 51.0% | 51.2% | 51.0% | 51.1% | 50.5% | <0.001 | 5,204,433 |
| First-born | 91.1% | 64.0% | 42.4% | 28.5% | 24.7% | 26.1% | <0.001 | 5,204,433 |
| Smoker at age 18a | 67.5% | 60.8% | 57.5% | 54.8% | 55.7% | 56.5% | <0.001 | 45,006 |
| Left-handeda | 8.6% | 8.6% | 8.4% | 8.2% | 8.4% | 8.3% | <0.001 | 1,304,248 |
| Date of birth | 1962 | 1962 | 1963 | 1961 | 1958 | 1954 | <0.001 | 5,204,433 |
| Birth weight (kg) | 3.4 | 3.5 | 3.5 | 3.5 | 3.5 | 3.5 | <0.001 | 1,377,985 |
| Birth length (cm) | 50.1 | 50.3 | 50.5 | 50.5 | 50.5 | 50.3 | <0.001 | 1,374,771 |
| Height at age 18 (cm)a | 178.3 | 179.0 | 179.6 | 179.8 | 179.6 | 179.2 | <0.001 | 1,592,625 |
| BMI at age 18 (kg m−2)a | 22.0 | 21.9 | 21.9 | 21.9 | 21.8 | 21.7 | <0.001 | 1,592,271 |
| SBP at age 18 (mm Hg)a | 127.7 | 128.3 | 128.7 | 128.9 | 128.9 | 128.9 | <0.001 | 1,517,662 |
| DBP at age 18 (mm Hg)a | 67.0 | 67.2 | 67.5 | 68.1 | 68.4 | 68.7 | <0.001 | 1,517,457 |
| Intelligence at age 18a | 4.6 | 4.9 | 5.3 | 5.3 | 5.3 | 5.1 | <0.001 | 1,648,011 |
| Non-cognitive ability at age 18a | 5.0 | 5.2 | 5.4 | 5.3 | 5.1 | 4.9 | <0.001 | 1,079,880 |
aMeasured in male offspring only, at military service medicals 1969-1970 (smoking) or 1969-2001 (other measurements).