Intergenerational influences on childhood body mass index: the effect of parental body mass index trajectories.

Background: Parental obesity in adulthood is a strong determinant of offspring obesity. Whether parental body mass index (BMI; in kg/m2) at earlier life stages is associated with offspring BMI is unknown.

Objective: The main objective was to assess whether recent BMI of parents in adulthood and their recent BMI gain are more strongly associated with offspring BMI than are BMI or changes in parental BMI in childhood.

Design: Two generations in the 1958 British birth cohort were studied, including cohort members (parents' generation) with BMI at 7, 11, 16, 23, and 33 y (n = 16,794) and a one-third sample of their offspring selected in 1991 aged 4-18 y (n = 2908). We applied multilevel models to allow for within-family correlations.

Results: Childhood BMI increased on average by 0.25-1.10 between the 2 generations, depending on sex and age group, and overweight/obesity increased from 10% to 16%. Parents' BMI in childhood and adulthood independently influenced offspring BMI, but no significant difference in the strength of influence was observed. For example, adjusted increase in BMI for offspring aged 4-8 y was equivalent to 0.37 and 0.23 for a 1-SD increase in maternal BMI at 7 and 33 y, respectively. Similar patterns were observed for risk of overweight/obesity and for paternal BMI at most ages.

Conclusions: Excessive BMI gains of parents during childhood and adulthood were associated with a higher BMI and risk of obesity in the offspring. Reductions in the incidence of child obesity in the current population may reduce obesity in future generations.