The association of the duration of breastfeeding with childhood obesity is equivocal. The first year of life is a period of hypertrophic expansion of adipocytes with little increase in adipocyte number. Hence, over-nutrition during this period could potentially result in persistent changes in adipocyte size that may last until adulthood. In this study, we have investigated the association of breastfeeding duration with abdominal fat distribution and adipose tissue cellularity at 4.5 years. Our results indicate a weak protective effect of longer breastfeeding duration on abdominal subcutaneous adipose tissue volumes and subcutaneous adipose tissue morphology.