The way a baby is born can have health effects that reach far beyond delivery day. Recent research suggests that infants born via cesarean section have an elevated risk of some chronic diseases, including asthma, obesity, and type 1 diabetes, as compared to babies delivered vaginally. One explanation for the puzzling health disparity is the type of microbes (tiny, single-cell organisms, including bacteria) babies are exposed to at birth. A baby born through the birth canal ends up with a superior microbial community—including bacteria thought to help regulate immune systems and protect against disease—than babies born via C-section.

In 2016, a team of scientists, including University of Colorado Boulder researcher Se Jin Song, tested a new technique that may help level the microbial playing field. Scientists swabbed babies born via C-section with their mothers’ vaginal fluids. Thirty days later, those babies had microbial communities living on and in their bodies that more closely resembled those of babies born vaginally. Although researchers have yet to determine if this type of procedure will translate into positive health impacts, women in Colorado and elsewhere have begun requesting it. But because such swabbing also has the potential to introduce infections, most labor and delivery wards—including University of Colorado Hospital, which has provided the service a few times on a case-by-case basis—say they’re waiting for the science to settle before they make this technique a standard practice.