Table 1. Characteristics of the two study populations The Copenhagen School Health Records Register (CSHRR) and The Draft Board (DB) given as median (5–95% interval) and in percentages.
| CSHRR | DB | |||
| Cases (BMI ≥95th percentile n = 1 460) | Controls (BMI <95th percentile n = 27 867) | Cases (BMI ≥31kg/m2 n = 323) | Controls (random sample n = 575) | |
| BMI (kg/m 2 ) | 25.3 (23.4–30.6)1 | 18.0 (15.2–22.1)1 | 32.7 (31.1–40.4)2 | 21.3 (18.3–25.9)2 |
| Family size | % | % | % | % |
| 1 (only child) | 21.5 | 16.2 | 18.3 | 13.0 |
| 2 | 47.1 | 48.3 | 40.6 | 45.4 |
| 3 | 21.4 | 25.4 | 20.7 | 26.6 |
| 4 | 7.9 | 7.5 | 11.8 | 7.5 |
| 5+ | 2.1 | 2.7 | 8.7 | 7.5 |
| Birth order | % | % | % | % |
| 1 | 54.5 | 58.1 | 43.3 | 45.7 |
| 2 | 33.3 | 32.3 | 31.0 | 33.2 |
| 3 | 9.6 | 8.4 | 14.6 | 12.2 |
| 4 | 2.6 | 1.2 | 7.1 | 4.9 |
| 5+ | 0.41 | 0.35 | 4.0 | 4.0 |
| Birth weight (g) | 3500 (2500–4350) | 3300 (2350–4200) | 3500 (2500–4750) | 3500 (2500–4500) |
| Year of birth | 1974 (1958–1988) | 1966 (1956–1986) | 1948 (1939–1956) | 1946 (1937–1955) |
| Birth spacing (days) 3 Mother’s BMI (kg/m 2 ) | 1624 (1033) 20.6 (2.9) | 1299 (868) 18.6 (2.3) | – | – |
| Mother’s age (years) | 25.4 (4.8) | 24.2 (4.4) | – | – |
| Father’s social class | % | % | % | % |
| Unskilled workers | – | – | 46.8 | 32.2 |
| Skilled | – | – | 49.9 | 61.4 |
| Academic | – | – | 3.4 | 6.4 |
1
at age 13 years,
2
at draft board examination (∼19 years),
3
between (consecutively born) sibling.