Baby’s First Poop Can Help Predict Allergies

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A study has shown that a baby’s first poop might hold the answers to whether the child will develop allergies later on.

A baby’s first poop, also called meconium begins forming in the fetal gut at around the 16th week of pregnancy. The sticky, dark green substance is a reflection of the fetus’s exposure during gestation. It contains cells, amniotic fluid, mucus, and other things the fetus may have ingested or excreted within the uterus. Moreover, the meconium also carries molecules called metabolites that are the starting material for the initial gut bacteria. Maturation of the gut bacteria occurs immediately after birth and plays a key role in the development of allergic diseases. Therefore, analysis of this gut bacteria has been a target of intense research.

Meconium is like a time capsule, revealing what the infant was exposed to before it was born. It contains all sorts of molecules encountered and accumulated from the mother while in the womb, and it then becomes the initial food source for the earliest gut microbes.

Dr Charisse Petersen, study’s lead author

Now, a team at the University of British Columbia (UBC) has found an association between a baby’s first poop and the risk of developing allergies within the first year of life. The researchers investigated the metabolites present within the meconium to identify factors associated with the development of allergies. They collected meconium samples from 100 infants enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) cohort study.

Petersen et al., 2021

Less Bacteria, Higher Risk

The team of researchers used a machine-learning algorithm to predict an infant’s risk of developing allergies by the age of one. They had an accuracy of about 76%.

Results showed the fewer metabolites within a baby’s meconium, the higher their risk of developing allergies. Moreover, low levels of certain metabolites affected the colonization of bacterial groups. These particular groups of bacteria played a role in the maturation of early-life gut bacteria. Additionally, infants who developed allergies by 1 year of age had less mature gut bacteria early in life.

This work shows that the development of a healthy immune system and microbiota may actually start well before a child is born—and signals that the tiny molecules an infant is exposed to in the womb play a fundamental role in future health.

Dr Charisse Petersen, study’s lead author

According to the study authors, identification of prenatal factors that determine the composition of meconium can help identify at-risk infants. Thus, leading to timely interventions and preventing the development of allergies.


Petersen et al., Cell Reports Medicine (2021),


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