Baby’s First Poop

Scientists are beginning to understand how the development of the gut microbiome, the microbes that colonize the gut, after birth may lead to or prevent development of childhood conditions that involve an immune response — such as eczema, asthma and food allergies. Over the past 50 years the prevalence of these types of autoimmune conditions has increased.

The findings of a new study suggest that a baby’s first poop, a thick, dark green substance called meconium, may provide clues about the association between the gut microbiome and allergy development. By studying clinical data and data from meconium samples of newborns, the researchers were able to predict with 76 percent accuracy if an infant would develop allergies by the time they turned one year old.

The fewer types of molecules a baby’s meconium contained, the more likely the baby was to develop allergies by its first birthday.

The findings may have important implications for babies at high risk of developing allergies, particularly children with asthma. “Now we have an opportunity to identify at-risk infants who might benefit from early interventions, before they show signs or symptoms of allergies or asthma later in life,” said Stuart Turvey, senior co-author on the study and a professor of pediatrics at the University of British Columbia (UBC).

Meconium starts forming in the fetal gut by the 16th week of gestation and contains all the different molecules encountered by the mother during pregnancy. It becomes the initial food source for bacteria that make up the baby’s gut microbiome, which begins developing right after birth and continues through the first few years of life. “Meconium is like a time capsule, revealing what the infant was exposed to before it was born,” first author, Charisse Petersen, explained.

It had been thought that the window for developing allergies, or allergic sensitization, occurred during a baby’s first year. But these findings suggest that exposures even before birth can influence health.

Meconium samples from 100 infants enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) cohort were analyzed for the study. The fewer types of molecules a baby’s meconium contained, the more likely the baby was to develop allergies by one year of age. And a smaller number of certain molecules meant changes to bacteria that play an important role in the development of the microbiota in the gut.

Most pregnant women probably already support their babies’ microbiota by eating a healthy, diverse diet, which includes carbs, proteins and fats from multiple sources, said Petersen, a research associate in the department of pediatrics at the University of British Columbia. “All of that is helpful.”

But to support babies’ gut health and reduce the risk of allergies and other autoimmune issues after babies are born, parents should aim for a sustained period of breastfeeding, and avoid unnecessary antibiotics, Petersen added.

It had been thought that the window for developing allergies, or allergic sensitization, occurred during a baby’s first year. But these findings suggest that exposures even before birth can influence health.

She also recommends that babies be allowed to play outdoors as much as possible, where, as long as lead pollution is not a problem, they can pick up helpful microbes from exposure to the soil. Parents might also want to relax cleaning standards a little, to reduce the exposure babies get to disinfectants. “All of these have been shown to help prevent allergies and maintain a healthy microbiota,” she said.

The UBC researchers hope to look at which metabolites or molecules in particular might be important for preventing allergy development. “Hopefully,” Petersen commented, “once we know those answers, we can make sure these molecules are present in a healthy diet or supplement to support pregnancy.”

The study is published in Cell Reports Medicine.