Early life body mass trajectories and mortality in older age: Findings from the Helsinki Birth Cohort Study

Background. Overweight and obesity in childhood have been linked to an increased risk of adult mortality, but evidence is still scarce. Methods. We identified trajectories of body mass index (BMI) development in early life and investigated their mortality risk. Data come from the Helsinki Birth Cohort Study, in which 4943 individuals, born 1934-1944, had serial measures of weight and height from birth to 11 years extracted from health care records, weight and height data in adulthood, and register-based mortality data for 2000-2010. Results. Three early BMI trajectories (increasing, average, and average-to-low for men and increasing, average, and low-to-high BMI for women) were identified. Women with an increasing or low-to-high BMI (BMI lower in early childhood, later exceeded average) trajectory had an increased risk of all-cause mortality compared to those with an average BMI trajectory (HR 1.55, 95% CI 1.07-2.23; and HR 1.57, 95% CI 1.04-2.37, respectively). Similar associations were observed for cancer mortality. Among men, BMI trajectories were not associated with all-cause mortality, but those with average-to-low BMI (BMI first similar then dropped below average) had an increased risk of cancer mortality. Conclusions. An increasing BMI in early life may shorten the lifespan of maturing cohorts as they age, particularly among women.