The relationship between parental locus of control and adolescent obesity: a longitudinal pre-birth cohort

Objectives: To investigate whether parental external locus of control (ELOC) measured in pregnancy is related to obesity in their adolescent offspring and whether the child’s own ELOC measured at age 8 contributes. To determine whether associations are due to types of behaviour used by externally oriented participants. Subjects/Methods: Longitudinal pre-birth cohort study (Avon Longitudinal Study of Parents & Children (ALSPAC)) set in south-west England. Families whose adolescent offspring had their fat mass measured using DXA scans at any of ages 9, 11, 13, 15 or 17 (range n=7329 at 9 to n=4850 at 17). The primary outcome measures were mean fat mass, and obesity measured as >85th centile of fat mass at each age. Results: We found that parent and child externality was associated with greater fat mass [e.g. mean difference at age 15 associated with maternal ELOC was 1.70kg (+1.17,+2.24), paternal ELOC 1.49kg (+0.89,+2.09) and child’s ELOC 1.50kg(+0.93,+2.06)(P<0.0001)]. Further analyses showed that factors associated with parent behaviour such as smoking in pregnancy, failure to breast feed, and early introduction of solids accounted for a third of the excess fat mass associated with maternal externality, whereas aspects of diet and energetic activity in later childhood were not. Further analyses demonstrated that the child’s own ELOC only became independently important for adolescent obesity from age 13, whereas the mothers’ and to a lesser extent the fathers’ ELOC were associated at each age. Conclusions: There is increased interest in determining factors that may be involved in the aetiology and maintenance of excessive weight in adolescents. We demonstrate that parental locus of control is a promising candidate. We suggest interventions to change parents’ locus of control toward internality in pregnancy might have long-term preventative benefits on the likelihood of obesity in the offspring.