Breastfeeding as an issue of significance in the world of public health and nutrition has gained considerable traction in recent months. With globally publicized opposition by the US to the World Health Assembly Resolution on Infant and Young Child Feeding (triggered by severe restrictions on milk products for older infants and young children) and reports of coercion to further corporate interests, the issue is of great pertinence in today’s times. It being World Breastfeeding Week, this blog will delve into the science of breastfeeding, a nutrition-focused behavior that has amassed a tremendous body of evidence in its favor when concerning infant and young child health .
The Lancet series published in 2016 describes both the micro and macro level benefits of breastfeeding for infants in countries of all economic strata. One paper  from the series estimates that approximately 823,000 annual deaths among children <5 years of age and 20,000 annual deaths of women from breast cancer can be avoided through the promotion of improved breastfeeding practices. Additionally, breastfeeding has long lasting impacts on morbidity and improves the cognitive capacity and educational potential of children, with economic benefits including higher wages in adulthood . Greater benefits are achieved with longer durations of breastfeeding, and this behavior has impact on morbidity with evidence showing protective benefits against diarrhea, respiratory infections, and asthma .
Additionally, a growing body of evidence shows overwhelming support for breastfeeding as protective behavior against long-term health outcomes related to non-communicable diseases including obesity . An analysis of 113 studies shows that longer durations of breastfeeding are associated with a 26% reduction (95% CI: 22-30) in the odds of obesity across income groups. Another pooled analysis of 11 studies showed a 35% reduction (95% CI: 14-51) in the incidence of type 2 diabetes . Prior work has shown that breastfeeding confers protection against obesity later in life, with lower prevalence rates after adjusting for confounders such as socioeconomic status, birthweight and sex .
Recent papers published in the American Journal of Clinical Nutrition highlight the nuanced impact of breastfeeding on child growth trajectories. A study by Kramer et al. (2018) showed, using various different statistical analyses, a causal effect of randomization to a breastfeeding promotion intervention on growth during the first 2-3 months of life . Additionally, these authors noted that children in a breastfeeding intervention group and those who were breastfed for ≥12 months experienced faster growth when compared to those in the control group or those breastfed for <12 months, particularly during the first 2-3 months. The differences in growth velocity between groups was lower in subsequent months and almost equalized by 12 months of age.
A study by Eny et al. conducted in Canada found that maternal BMI was positively correlated to infant BMI . These authors note that maternal BMI has been shown to modify BMI growth rates among children beginning at birth up to 12 years of age . These authors note that the trajectories for growth differed by breastfeeding duration, maternal BMI and birth weight from 1-3 months of age.
Results from these studies and others highlight the need for more prospective research to assess how, when and whether breastfeeding practices influence infant weight gain, and what factors within breastmilk impact lean and fat mass growth . Overall, the case for early initiation, exclusivity of breastfeeding for the first 6 months and continued breastfeeding up to 2 years remain strong and programs, policies and incentives to encourage and promote adequate breastfeeding behaviors remain the need of the hour. So this World Breastfeeding Week, may mothers’ across the world be motivated, encouraged and supported to continue gifting their young one of the most valuable gifts nature has accorded us!
 Jacobs, A. (2018). Opposition to breast-feeding resolution by the US stuns world health officials. Retrieved from: https://www.nytimes.com/2018/07/08/health/world-health-breastfeeding-ecuador-trump.html
 Rollins, N.C., Bhandari, N., Hajeebhoy, N., Horton, S., Lutter, C.K., Martines, J.C., Piwoz, E.G., Richter, L.M., Victora, C.G. (2016). Why invest, and what it will take to improve breastfeeding practices? Lancet, 387, 491-504.
 Victora, C.G., Bahl, R., Barros, A.J., Franca, G.V.A., Horton, S., Krasevec, J., Murch, S., Sankar, M.J., Walker, N., Rollins, N.C. (2016). Breastfeeding in the 21st century: epidemiology, mechanisms, and lifelong effect. Lancet, 287, 475-490.
 Armstrong, J., Reilly, J.J., & Child Health Information Team. (2002). Breastfeeding and lowering the risk of childhood obesity. Lancet, 359 (9322), 2003-2004.
 Kramer, M.S., Davies, N., Oken, E., Martin, R.M., Dahhou, M., Zhang, X., & Yang, S. (2018). Infant feeding and growth: putting the horse before the cart. American Journal of Clinical Nutrition, 107, 635-639.
 Eny, K.M., Anderson, L.N., Chen, Y., Lebovic, G., Pullenayegum, E., Parkin, P.C., Maguire, J.L., Birken, C.S. (2018). Breastfeeding duration, maternal body mass index, and birth weight are associated with differences in body mass index growth trajectories in early childhood. American Journal of Clinical Nutrition, 107, 584-592.
 Bornhorst, C., Siani, A., Russo, P., Kourides, Y., Sion, I., Molnar, D., Moreno, L.A., Rodrigues, G., Ben-Shlomo, Y., Howe, L., et al. (2016). Early life factors and inter-country heterogeneity in BMI growth trajectories of European children: the IDEFICS study. PLoS One, 2016:11:e0149268.
 Hay, W.W. Jr. (2018). Breastfeeding newborns and infants: some new food for thought about an old practice. American Journal of Clinical Nutrition, 107, 499-500.