Body mass index, adiposity rebound and early feeding in a longitudinal cohort (Raine Study)

Objective: This study examined the influence of type and duration of infant feeding on adiposity rebound and the tracking of body mass index (BMI) from birth to 14 years of age. Methods: A sample of 1330 individuals over eight follows-ups was drawn from the Western Australian Pregnancy Cohort (Raine) Study. Trajectories of BMI from birth to adolescence using linear mixed model analysis investigated the influence of age at which breastfeeding was stopped and the age at which other milk was introduced (binomial 4-month cutoff point). A subsample of linear mixed model-predicted BMI was used to determine BMI and age at nadir for early infant feeding groups. Results: Chi-square analysis between early feeding and weight status (normal weight, overweight and obese) groups found a significant difference between thee age at which breastfeeding was stopped (P<0.001) and the age at which other milk was introduced (P = 0.011), with a higher proportion of overweight and obese in the <= 4-month group, even after controlling for maternal education. Using the linear mixed model, the BMI determined was higher over time for the group that was breastfed for <= 4 months (P = 0.015), with a significant interaction effect with the group in which other milk was introduced at <= 4 months (P = 0.011). Using predicted BMI from the linear mixed model, significant differences for nadirs of adiposity rebound between early feeding groups were found (P<0.005). Conclusions: Early infant feeding was important in the timing of, and BMI at, adiposity rebound. The relationship between infant feeding and BMI remained up to the age of 14 years. Although confounding factors cannot be excluded, these findings support the importance of exclusive breastfeeding for longer than 4 months as a protective behaviour against the development of adolescent obesity. International Journal of Obesity (2010) 34, 1169-1176; doi: 10.1038/ijo.2010.61; published online 30 March 2010