New parents who find themselves surprisingly attentive to their babies’ poop are in good company. Researchers at The Children’s Hospital of Philadelphia and the University of Pennsylvania are beginning the second phase of a study that is exploring whether baby poop is an important data source to learn how the risk of obesity develops early in life.

The research team is focused on the miniscule but mighty passengers in baby poop: the gut microbiome. The collection of bacteria and other microorganisms that live within the digestive tract and contribute to processing food could reveal a lot about early excess weight gain.