Breast, Formula and Combination Feeding in Relation to Childhood Obesity in Nova Scotia, Canada.

Breastfeeding has been rigorously studied in relation to childhood obesity prevention. Few studies have examined whether combination feeding—breast milk and formula—may also be protective against obesity. This study aimed to investigate the relationship between breastfeeding duration, combination feeding and overweight and obesity among Canadian school children. We analyzed data from a 2011 cross-sectional, population based survey (n = 5,560), which included self-reported infant feeding behaviours, a food frequency questionnaire and measured height and weight. Multilevel regression methods were used to examine the association between breastfeeding duration and overweight and obesity adjusting for socioeconomic status, diet quality and physical activity. Thirty-four percent of children were breastfed for <1 week or never while 32% were breastfed for at least 6 months. In the fully adjusted model, children who were only formula fed or who were combination fed for <6 months were more likely to be overweight or obese relative to children who were only breastfed (OR 1.29, 95% CI 1.04-1.60 and OR 1.35, 95% CI 1.09-1.69, respectively). When examining overweight and obese children separately, those who were only formula fed were more likely obese (OR 1.57, 95% CI 1.10-2.25) relative to their peers who were only breastfed. And those who were combination fed for <6 months relative to those only breastfed were more likely to be overweight (OR 1.29, 95% CI 1.01-1.66). Breastfeeding, in the absence of formula feeding, appears to have a protective effect on childhood obesity. While combination feeding confers less benefit than only breastfeeding, it is more desirable than formula feeding alone. Strategies and social policies are needed to promote exclusive and longer breastfeeding duration and should be integrated with comprehensive efforts to prevent childhood obesity and to reduce the burden of chronic diseases in the long term.