Mean body mass index (BMI kg/m2), prevalence (%) of low weight (BMI<20 kg/m2) and obesity (BMI≥30 kg/m2) as well as mean change in BMI (95% CI) according to 5-year birth cohorts in 5 229 women who participated in Tromsø 4 (1994–1995) and Tromsø 6 (2007–2008)
| BMI | ||||||||
|---|---|---|---|---|---|---|---|---|
| Tromsø 4 | Tromsø 6 | |||||||
| Birth cohort | n | Mean (SD) | Per cent <20 | Per cent ≥30 | Mean (SD) | Per cent <20 | Per cent ≥30 | Change (95% CI) |
| 1965–1969 | 597 | 23.2 (3.5) | 13.1 | 5.4 | 25.9 (4.5) | 5.4 | 17.1 | 2.7 (2.5 to 2.9) |
| 1960–1964 | 434 | 23.4 (3.6) | 12.4 | 5.3 | 25.7 (4.6) | 5.8 | 16.1 | 2.3 (2.0 to 2.5) |
| 1955–1959 | 480 | 23.8 (3.7) | 8.8 | 5.8 | 26.0 (4.4) | 2.7 | 16.3 | 2.2 (2.0 to 2.4) |
| 1950–1954 | 521 | 24.2 (3.9) | 8.3 | 8.5 | 26.3 (4.6) | 4.2 | 17.9 | 2.0 (1.8 to 2.2) |
| 1945–1949 | 936 | 25.0 (3.9) | 4.7 | 10.7 | 26.9 (4.4) | 3.1 | 21.4 | 1.9 (1.7 to 2.1) |
| 1940–1944 | 901 | 25.4 (4.2) | 5.2 | 13.3 | 27.2 (4.9) | 2.9 | 22.6 | 1.8 (1.6 to 2.0) |
| 1935–1939 | 607 | 25.8 (4.1) | 3.8 | 14.2 | 27.0 (4.6) | 4.0 | 23.4 | 1.2 (1.0 to 1.4) |
| 1930–1934 | 438 | 25.9 (3.7) | 3.0 | 13.0 | 26.9 (4.4) | 4.3 | 22.6 | 1.0 (0.8 to 1.2) |
| 1925–1929 | 315 | 26.4 (9.9) | 3.8 | 18.7 | 27.1 (4.5) | 4.8 | 26.4 | 0.7 (0.4 to 0.9) |
| Total | 5229 | 24.8 (4.0) | 6.8 | 10.5 | 26.6 (4.6) | 3.9 | 20.5 | 1.8 (1.7 to 1.9) |
| P value* | <0.001 | <0.001 | <0.001 | <0.001 | 0.2 | <0.001 | <0.001 | |
*P value for linear trend over the birth cohorts.