The MILK Study

Supported by the Wenner Gren Foundation, Yale University Smith Fund, Yale MacMillan Center Dissertation Fellowship, and Yale Institute of Biospheric Studies

  • While originally viewed as a one-way process, human milk and breastfeeding is now known to be a dynamic exchange of information between mother and child. One process enabled through breastfeeding is the development of infant hunger and satiety regulation through the transfer of bioactive hormones that play a role in overweight/obesity risk in adulthood. To explore this in Samoa, we considered the questions: 1) How is maternal body composition associated with human milk metabolic hormone composition? 2) How do human milk metabolic hormone levels mediate infant satiety, growth, and body composition? and 3) how does infant biological sex mediate milk transfer from mother to infant?

  • The study involved six visits: two each at 1-, 3-, and 4-months postpartum. At each timepoint, physical measurements of mother and baby were taken and a breastmilk sample collected at the first visit. At the second visit, questionnaires were completed and a short interview was conducted while the mother was observed breastfeeding her baby. You can download our protocol paper here!

  • With the high rates of obesity continuing to rise in Samoa, this project presents the opportunity to understand early-life mechanisms potentially contributing to the high prevalence of obesity/adiposity and subsequent non-communicable diseases in the population.

  • Recruitment took place from April 2023 - July 2024. In total 77 mothers and their babies completed all data collection.

  • Once we have the results finalized, we will work closely with the public health departments and the Nutritional Surveillance Department in Samoa. We hope to use the findings to help create public health messages that tailor culturally specific nutritional information about human milk to mothers; promoting a healthy maternal diet during breastfeeding and encouraging healthy infant satiety and hunger hormonal development that will be beneficial throughout life.

  • Please keep an eye out for our publications! For more information about the study, please email Principal Investigators Victoria Bertacchi (victoria.harries@yale.edu) and Dr. Nicola Hawley (nicola.hawley@yale.edu).