A new study led by Winnipeg researchers suggests hormones found in breast milk may play a role in preventing obesity in infants.

The study measured the concentrations of three hormones, adiponectin, leptin and insulin, in the breast milk of 430 moms, as well as the size of their babies. It found that high concentrations of leptin and intermediate concentrations of insulin were linked with lower waist-for-length measurements and body mass index scores in infants.

“Human milk is an incredibly complex biological substance,” said the study’s lead, Dr. Meghan Azad, associate professor, University of Manitoba and research scientist, Children’s Hospital Research Institute of Manitoba, in a news release. 

The study’s results also suggest that there are factors that can influence hormone concentrations in breast milk, including the age and ethnicity of the mother and whether or not she breastfed exclusively.

The World Health Organization recommends breastfeeding exclusively for the first six months of a baby’s life.