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Accepted for/Published in: JMIR Research Protocols

Date Submitted: Mar 18, 2026
Open Peer Review Period: Mar 19, 2026 - Apr 30, 2026
Date Accepted: May 29, 2026
(closed for review but you can still tweet)

The final, peer-reviewed published version of this preprint can be found here:

Exploring the Early-Life Microbiomes of Preterm Infants and Their Childhood Health Outcomes (The BLOOM Study): Protocol for a Prospective, Observational Cohort Study

Arrieta MC, Guedez A, Alshaikh B, Lebel C, Mercer EM, Kasaba F, Giesbrecht G, Zein H, Kellner J, Samara J, Leijser L, Sycuro L, Hendson L, Murguia Favela L, Asbury M, Lacaze-Masmontiel T, Rangipour Z, Lee J, McNagny K

Exploring the Early-Life Microbiomes of Preterm Infants and Their Childhood Health Outcomes (The BLOOM Study): Protocol for a Prospective, Observational Cohort Study

JMIR Res Protoc 2026;15:e95658

DOI: 10.2196/95658

PMID: 42612036

The BLOOM Study: Protocol for a prospective, observational cohort study exploring the early-life microbiomes of preterm infants and their childhood health outcomes

  • Marie-Claire Arrieta; 
  • Andrea Guedez; 
  • Belal Alshaikh; 
  • Catherine Lebel; 
  • Emily M Mercer; 
  • Fatimoh Kasaba; 
  • Gerald Giesbrecht; 
  • Hussein Zein; 
  • James Kellner; 
  • Jumana Samara; 
  • Lara Leijser; 
  • Laura Sycuro; 
  • Leonora Hendson; 
  • Luis Murguia Favela; 
  • Michelle Asbury; 
  • Thierry Lacaze-Masmontiel; 
  • Zahra Rangipour; 
  • Jessica Lee; 
  • Kelly McNagny

ABSTRACT

Background:

Background:

Establishment of the gut microbiome during the first years of life is critically important for long-term health and development. In preterm infants, microbial colonization is disrupted due to their developmental immaturity and the myriad of pre- and postnatal exposures. Unfortunately, this places them at an elevated risk for adverse health outcomes into childhood (e.g., asthma, impaired neurodevelopment). Understanding the developmental trajectory of the microbiome in preterm infants, the factors predicting these microbial patterns, and the links to childhood health can offer opportunities to develop interventions and optimize health.

Objective:

To comprehensively study microbiome development in preterm infants and understand how microbial patterns during this critical early-life window contribute to development and disease risk in childhood.

Methods:

Methods:

BLOOM (Begin a Life of Health with Observation and Optimization of the Microbiome) is a prospective, observational cohort study that aims to examine how early-life microbiomes shape the health and development of preterm infants into childhood (e.g., asthma, neurodevelopment). Infants (<37 weeks gestation) and their families are recruited from 4 neonatal intensive care units in Calgary, Alberta, Canada. Maternal stool and weekly infant stool, urine, and human milk samples are collected during the first 2 months postnatally; participants are then followed up at 3 months, 1 year, and 3 years corrected age for continued data (e.g., nutrition, medications, medical history, home environment) and sample collection (stool, urine, nasal swabs, hair, and blood). Additional clinical testing (e.g., allergen skin prick test) and questionnaires (e.g., Ages & Stages Questionnaire-) are administered to assess health outcomes and developmental milestones. Study recruitment commenced in 2019 and is ongoing.

Results:

To date, we have enrolled 245 participants.

Conclusions:

Discussion: BLOOM is a large, comprehensive prospective cohort study and biobank aimed at measuring the microbiome development of preterm-born children. This cohort will address significant research priorities through characterizing the patterns of microbiome development in preterm infants over the first 3-years postnatally and correlating these with health outcomes (e.g., immune development, asthma and allergy risks, neurodevelopment). It is anticipated that the results can be leveraged to identify factors and altered microbiome patterns underlying disease risk, design intervention strategies (e.g., microbial therapeutics) for later clinical testing, and generate novel hypotheses of possible underlying mechanisms linking microbiome development to health. Clinical Trial: Trial Registration: clinicaltrials.gov (NCT03840980, registration date 2019-02-11; NCT04641000, registration date 2020-11-17; NCT05011071, registration date 2021-08-11).


 Citation

Please cite as:

Arrieta MC, Guedez A, Alshaikh B, Lebel C, Mercer EM, Kasaba F, Giesbrecht G, Zein H, Kellner J, Samara J, Leijser L, Sycuro L, Hendson L, Murguia Favela L, Asbury M, Lacaze-Masmontiel T, Rangipour Z, Lee J, McNagny K

Exploring the Early-Life Microbiomes of Preterm Infants and Their Childhood Health Outcomes (The BLOOM Study): Protocol for a Prospective, Observational Cohort Study

JMIR Res Protoc 2026;15:e95658

DOI: 10.2196/95658

PMID: 42612036

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