Background Cardiovascular disease (CVD) is a major public health problem. Clinical trials have shown that lowering total- and/or low-density lipoprotein (LDL)-cholesterol reduces the risk of CVD. Therefore, to reduce the burden of CVD, improvement in lipid profiles is an important goal. To achieve this, a better understanding is needed of biological pathways leading to lipid levels. Lipid levels track from childhood to adulthood, implying that influences on adult cholesterol levels begin at young ages. There is scant evidence on the role of growth, including trajectories of body mass index (BMI) across the life-course with respect to lipids. We aimed to determine whether there are phases of the life-course that are particularly important for adult lipid levels.
Methods In the 1958 British Birth Cohort weight and height were recorded at birth (weight only), 7y, 11y, 16y, 23y, 33y and 45y. In 3,927 men and 3,897 women we assessed whether (i) birthweight was associated with 45y lipids and whether associations were due to catch-up growth to 7y; (ii) there were particular periods when BMI, or change in BMI, influenced subsequent lipid levels; (iii) associations between current BMI and lipid levels were modified by BMI at younger ages; and (iv) duration of obesity was associated with lipid levels. Analyses were sex specific, adjusted for covariates and used multiple imputation to account for missing data.
Results Birthweight was inversely associated with triglycerides and in women with total- and LDL-cholesterol; associations persisted after adjustment for 7y BMI. Associations with lipids strengthened with age of BMI measurement, e.g. per standard deviation (SD) higher BMI at 11y and 45y triglycerides were higher by 4.01% (95% confidence interval: 2.26%, 5.75%) and 19.75% (18.18%, 21.32%) respectively in women. BMI change was related to lipids, with strongest associations for the interval preceding lipid measurement: per SD increase in BMI 33–45y total-cholesterol and triglycerides were higher by ∼3% and ∼21% respectively. Associations between 45y BMI and lipids were stronger for those with lower than higher BMI at younger ages (P for interactions: <0.01 to ≤0.05). This effect-modification was seen from childhood (7y in women; 11y in men). Obesity in childhood but not thereafter and longer duration of obesity were unrelated to adult lipid levels.
Conclusion Our study suggests that life-course trajectories of body size influence adult lipid levels, with the consequences of a high adult BMI for adult lipid levels being particularly adverse for those with lower BMI at earlier life-stages.