Gut Microbiota and Metabolic Development in Early Childhood: A 3-Year Follow-Up Study

Early childhood is a critical period for the establishment and maturation of the gut microbiome. Microbiome development during this period may be influenced by maternal health, pregnancy-related factors, mode of delivery, gestational age, infant feeding, medication exposure, infections, household conditions, and other early-life exposures.

This prospective, longitudinal, observational birth cohort study will recruit approximately 1000 pregnant women and follow their children from birth to 36 months of age. No intervention will be assigned by the investigators, and participants will receive routine maternal and child healthcare according to local clinical practice.

Information on parental demographic, health, anthropometric, and lifestyle characteristics; maternal pre-pregnancy and pregnancy-related factors; prenatal examinations; delivery and neonatal characteristics; infant feeding and diet; medication use; illnesses; vaccination; hospitalization; and household and environmental factors will be collected through questionnaires and medical records. Child growth will be assessed using standardized anthropometric measurements.

Fecal samples will be collected at birth and at 1, 3, 6, 9, 12, 18, 24, and 36 months of age using standardized procedures. Shotgun metagenomic sequencing will be used to characterize the taxonomic composition and functional potential of the gut microbiome and to evaluate its longitudinal developmental patterns.

Umbilical cord blood collection will be planned at delivery for all participants, subject to informed consent, collection feasibility, and institutional procedures. At 36 months of age, residual venous blood remaining after routine health examinations and clinically indicated laboratory testing may be retained for research. All biological specimens will be processed and stored according to standardized operating procedures.

Longitudinal statistical methods will be used to evaluate age-related microbiome changes and their associations with early-life exposures and child outcomes. Analyses will account for repeated measurements, relevant potential confounders, missing data, loss to follow-up, multiple comparisons, and the compositional nature of microbiome data. Exploratory analyses may assess whether gut microbiome characteristics mediate or modify associations between early-life exposures and subsequent child outcomes.

As this is an observational study, identified associations will not by themselves establish causal relationships. The study is expected to provide evidence on gut microbiome development during early childhood and to inform future mechanistic and preventive research.

Inclusion criteria

• Willing to undergo regular follow-up during the study period

Exclusion criteria

• Difficulty in follow-up participation