Table 6

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 4Tromsø 6
Birth cohortnMean (SD)Per cent <20Per cent ≥30Mean (SD)Per cent <20Per cent ≥30Change (95% CI)
1965–196959723.2 (3.5)13.15.425.9 (4.5)5.417.12.7 (2.5 to 2.9)
1960–196443423.4 (3.6)12.45.325.7 (4.6)5.816.12.3 (2.0 to 2.5)
1955–195948023.8 (3.7)8.85.826.0 (4.4)2.716.32.2 (2.0 to 2.4)
1950–195452124.2 (3.9)8.38.526.3 (4.6)4.217.92.0 (1.8 to 2.2)
1945–194993625.0 (3.9)4.710.726.9 (4.4)3.121.41.9 (1.7 to 2.1)
1940–194490125.4 (4.2)5.213.327.2 (4.9)2.922.61.8 (1.6 to 2.0)
1935–193960725.8 (4.1)3.814.227.0 (4.6)4.023.41.2 (1.0 to 1.4)
1930–193443825.9 (3.7)3.013.026.9 (4.4)4.322.61.0 (0.8 to 1.2)
1925–192931526.4 (9.9)3.818.727.1 (4.5)4.826.40.7 (0.4 to 0.9)
Total522924.8 (4.0)6.810.526.6 (4.6)3.920.51.8 (1.7 to 1.9)
P value*<0.001<0.001<0.001<0.0010.2<0.001<0.001
  • *P value for linear trend over the birth cohorts.